given the following bpmn xml, why, when simulated, does the 'wait for bunned burger' event create two tokens?

<?xml version="1.0" encoding="UTF-8"?>
<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1ivadvu" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.10.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="8.2.0">
  <bpmn:signal id="Signal_3g047lo" name="cooked" />
  <bpmn:signal id="Signal_3k7259n" name="bunned" />
  <bpmn:collaboration id="Collaboration_1gefoe9">
    <bpmn:participant id="Participant_131vw02" name="grill" processRef="Process_1rqzogq" />
    <bpmn:participant id="Participant_1oqnwtq" name="pro burger eater" processRef="Process_1grciu6" />
    <bpmn:participant id="Participant_06qbjdz" name="bun toaster" processRef="Process_0vf04yq" />
  </bpmn:collaboration>
  <bpmn:process id="Process_1rqzogq" isExecutable="true">
    <bpmn:task id="Activity_15ie9s6" name="cook burger">
      <bpmn:incoming>Flow_1knhcse</bpmn:incoming>
      <bpmn:incoming>Flow_1wzvagi</bpmn:incoming>
      <bpmn:outgoing>Flow_0fwxddp</bpmn:outgoing>
    </bpmn:task>
    <bpmn:intermediateThrowEvent id="Event_1sqder9" name="burger cooked">
      <bpmn:incoming>Flow_0fwxddp</bpmn:incoming>
      <bpmn:outgoing>Flow_0ydp8pr</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_157g2bv" signalRef="Signal_3g047lo" />
    </bpmn:intermediateThrowEvent>
    <bpmn:startEvent id="Event_0tthm9t" name="start burger eating competition">
      <bpmn:outgoing>Flow_1wzvagi</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:intermediateCatchEvent id="Event_1b1h91h" name="wait for burger to be eaten">
      <bpmn:incoming>Flow_0ydp8pr</bpmn:incoming>
      <bpmn:outgoing>Flow_1knhcse</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_18kbhm4" signalRef="Signal_3k7259n" />
    </bpmn:intermediateCatchEvent>
    <bpmn:subProcess id="Activity_1ygir8m" name="Burger Eater is Full Process" triggeredByEvent="true">
      <bpmn:endEvent id="Event_00xzkxc" name="Stop cooking burgers">
        <bpmn:incoming>Flow_06670sp</bpmn:incoming>
      </bpmn:endEvent>
      <bpmn:sequenceFlow id="Flow_06670sp" sourceRef="Event_02b7nda" targetRef="Event_00xzkxc" />
      <bpmn:startEvent id="Event_02b7nda" name="Eater is full">
        <bpmn:outgoing>Flow_06670sp</bpmn:outgoing>
        <bpmn:signalEventDefinition id="SignalEventDefinition_1v6y5mv" signalRef="Signal_2af3m6h" />
      </bpmn:startEvent>
    </bpmn:subProcess>
    <bpmn:sequenceFlow id="Flow_1knhcse" sourceRef="Event_1b1h91h" targetRef="Activity_15ie9s6" />
    <bpmn:sequenceFlow id="Flow_1wzvagi" sourceRef="Event_0tthm9t" targetRef="Activity_15ie9s6" />
    <bpmn:sequenceFlow id="Flow_0fwxddp" sourceRef="Activity_15ie9s6" targetRef="Event_1sqder9" />
    <bpmn:sequenceFlow id="Flow_0ydp8pr" sourceRef="Event_1sqder9" targetRef="Event_1b1h91h" />
  </bpmn:process>
  <bpmn:process id="Process_1grciu6" isExecutable="false">
    <bpmn:task id="Activity_1vwt243" name="eat burger">
      <bpmn:incoming>Flow_0drv4b2</bpmn:incoming>
      <bpmn:incoming>Flow_03yvaod</bpmn:incoming>
      <bpmn:outgoing>Flow_14zlx8z</bpmn:outgoing>
    </bpmn:task>
    <bpmn:sequenceFlow id="Flow_0drv4b2" sourceRef="Event_0f03yzd" targetRef="Activity_1vwt243" />
    <bpmn:sequenceFlow id="Flow_03yvaod" sourceRef="Event_0f03yzd" targetRef="Activity_1vwt243" />
    <bpmn:startEvent id="Event_0f03yzd" name="wait for bunned burger">
      <bpmn:outgoing>Flow_03yvaod</bpmn:outgoing>
      <bpmn:outgoing>Flow_0drv4b2</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_1r6o8pn" signalRef="Signal_3k7259n" />
    </bpmn:startEvent>
    <bpmn:endEvent id="Event_1kh9qk0" name="Stop eating Burgers">
      <bpmn:incoming>Flow_1jz6lra</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:intermediateThrowEvent id="Event_0yys6ad">
      <bpmn:incoming>Flow_1ub7a2r</bpmn:incoming>
      <bpmn:outgoing>Flow_1jz6lra</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_1fojs7s" signalRef="Signal_2af3m6h" />
    </bpmn:intermediateThrowEvent>
    <bpmn:sequenceFlow id="Flow_1jz6lra" sourceRef="Event_0yys6ad" targetRef="Event_1kh9qk0" />
    <bpmn:boundaryEvent id="Event_0lxeyup" name="Reached Maximum Capacity" attachedToRef="Activity_1vwt243">
      <bpmn:outgoing>Flow_1ub7a2r</bpmn:outgoing>
      <bpmn:errorEventDefinition id="ErrorEventDefinition_025vb0t" errorRef="Error_0ee9akd" />
    </bpmn:boundaryEvent>
    <bpmn:sequenceFlow id="Flow_1ub7a2r" sourceRef="Event_0lxeyup" targetRef="Event_0yys6ad" />
    <bpmn:sequenceFlow id="Flow_14zlx8z" sourceRef="Activity_1vwt243" targetRef="Event_0lhgh13" />
    <bpmn:endEvent id="Event_0lhgh13" name="Ready for next burger">
      <bpmn:incoming>Flow_14zlx8z</bpmn:incoming>
      <bpmn:signalEventDefinition id="SignalEventDefinition_0w1yap4" signalRef="Signal_0t9hlhi" />
    </bpmn:endEvent>
  </bpmn:process>
  <bpmn:process id="Process_0vf04yq" isExecutable="false">
    <bpmn:intermediateThrowEvent id="Event_1jz4r5s" name="put burger in bun">
      <bpmn:extensionElements />
      <bpmn:incoming>Flow_1ts1677</bpmn:incoming>
      <bpmn:outgoing>Flow_0b4i0dt</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_1pww9z6" signalRef="Signal_3k7259n" />
    </bpmn:intermediateThrowEvent>
    <bpmn:task id="Activity_0bljabb" name="Put cooked burger in steam pan to keep warm">
      <bpmn:incoming>Flow_13lht1w</bpmn:incoming>
      <bpmn:outgoing>Flow_0cozu8t</bpmn:outgoing>
    </bpmn:task>
    <bpmn:task id="Activity_0hfz9ju" name="toast a bun">
      <bpmn:incoming>Flow_0cozu8t</bpmn:incoming>
      <bpmn:outgoing>Flow_1ts1677</bpmn:outgoing>
    </bpmn:task>
    <bpmn:sequenceFlow id="Flow_1ts1677" sourceRef="Activity_0hfz9ju" targetRef="Event_1jz4r5s" />
    <bpmn:sequenceFlow id="Flow_13lht1w" sourceRef="Event_06rx0lx" targetRef="Activity_0bljabb" />
    <bpmn:sequenceFlow id="Flow_0cozu8t" sourceRef="Activity_0bljabb" targetRef="Activity_0hfz9ju" />
    <bpmn:startEvent id="Event_06rx0lx" name="wait for cooked burger">
      <bpmn:outgoing>Flow_13lht1w</bpmn:outgoing>
      <bpmn:signalEventDefinition id="SignalEventDefinition_0vdv0rh" signalRef="Signal_3g047lo" />
    </bpmn:startEvent>
    <bpmn:sequenceFlow id="Flow_0b4i0dt" sourceRef="Event_1jz4r5s" targetRef="Event_03mk3ac" />
    <bpmn:endEvent id="Event_03mk3ac" name="Burger Bunned">
      <bpmn:incoming>Flow_0b4i0dt</bpmn:incoming>
    </bpmn:endEvent>
  </bpmn:process>
  <bpmn:error id="Error_0ee9akd" name="full" errorCode="full" />
  <bpmn:signal id="Signal_2af3m6h" name="full" />
  <bpmn:signal id="Signal_0t9hlhi" name="eaten" />
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Collaboration_1gefoe9">
      <bpmndi:BPMNShape id="Participant_131vw02_di" bpmnElement="Participant_131vw02" isHorizontal="true">
        <dc:Bounds x="155" y="90" width="695" height="530" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_15ie9s6_di" bpmnElement="Activity_15ie9s6">
        <dc:Bounds x="440" y="480" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1leop7o_di" bpmnElement="Event_1sqder9">
        <dc:Bounds x="632" y="502" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="624" y="543" width="71" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0tthm9t_di" bpmnElement="Event_0tthm9t">
        <dc:Bounds x="332" y="502" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="305" y="466" width="90" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0mjv9ij_di" bpmnElement="Event_1b1h91h">
        <dc:Bounds x="472" y="402" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="449" y="366" width="82" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0ovw6ve_di" bpmnElement="Activity_1ygir8m" isExpanded="true">
        <dc:Bounds x="225" y="120" width="350" height="200" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_00xzkxc_di" bpmnElement="Event_00xzkxc">
        <dc:Bounds x="482" y="202" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="471" y="246" width="64" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0szw0d0_di" bpmnElement="Event_02b7nda">
        <dc:Bounds x="252" y="202" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="243" y="245" width="55" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_06670sp_di" bpmnElement="Flow_06670sp">
        <di:waypoint x="288" y="220" />
        <di:waypoint x="482" y="220" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_1knhcse_di" bpmnElement="Flow_1knhcse">
        <di:waypoint x="490" y="438" />
        <di:waypoint x="490" y="480" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_1wzvagi_di" bpmnElement="Flow_1wzvagi">
        <di:waypoint x="368" y="520" />
        <di:waypoint x="440" y="520" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0fwxddp_di" bpmnElement="Flow_0fwxddp">
        <di:waypoint x="540" y="520" />
        <di:waypoint x="632" y="520" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0ydp8pr_di" bpmnElement="Flow_0ydp8pr">
        <di:waypoint x="650" y="502" />
        <di:waypoint x="650" y="420" />
        <di:waypoint x="508" y="420" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="Participant_1oqnwtq_di" bpmnElement="Participant_1oqnwtq" isHorizontal="true">
        <dc:Bounds x="950" y="432" width="710" height="288" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_1vwt243_di" bpmnElement="Activity_1vwt243">
        <dc:Bounds x="1240" y="590" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0p2k04l_di" bpmnElement="Event_0f03yzd">
        <dc:Bounds x="1142" y="612" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1122" y="576" width="75" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1kh9qk0_di" bpmnElement="Event_1kh9qk0">
        <dc:Bounds x="1452" y="482" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1442" y="446" width="56" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0zpjo6x_di" bpmnElement="Event_0yys6ad">
        <dc:Bounds x="1342" y="482" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1xym196_di" bpmnElement="Event_0lhgh13">
        <dc:Bounds x="1402" y="612" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1384" y="655" width="73" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1qwv6xq_di" bpmnElement="Event_0lxeyup">
        <dc:Bounds x="1282" y="572" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1246" y="530" width="48" height="40" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_0drv4b2_di" bpmnElement="Flow_0drv4b2">
        <di:waypoint x="1178" y="630" />
        <di:waypoint x="1240" y="630" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_03yvaod_di" bpmnElement="Flow_03yvaod">
        <di:waypoint x="1178" y="630" />
        <di:waypoint x="1240" y="630" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_1jz6lra_di" bpmnElement="Flow_1jz6lra">
        <di:waypoint x="1378" y="500" />
        <di:waypoint x="1452" y="500" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_1ub7a2r_di" bpmnElement="Flow_1ub7a2r">
        <di:waypoint x="1300" y="572" />
        <di:waypoint x="1300" y="500" />
        <di:waypoint x="1342" y="500" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_14zlx8z_di" bpmnElement="Flow_14zlx8z">
        <di:waypoint x="1340" y="630" />
        <di:waypoint x="1402" y="630" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="Participant_06qbjdz_di" bpmnElement="Participant_06qbjdz" isHorizontal="true">
        <dc:Bounds x="940" y="50" width="600" height="328" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_0xa2j9s_di" bpmnElement="Event_1jz4r5s">
        <dc:Bounds x="1202" y="300" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1178" y="283" width="84" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0bljabb_di" bpmnElement="Activity_0bljabb">
        <dc:Bounds x="1170" y="168" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0hfz9ju_di" bpmnElement="Activity_0hfz9ju">
        <dc:Bounds x="1330" y="168" width="100" height="80" />
        <bpmndi:BPMNLabel />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1omi59t_di" bpmnElement="Event_06rx0lx">
        <dc:Bounds x="1012" y="190" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="993" y="156" width="73" height="27" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_03mk3ac_di" bpmnElement="Event_03mk3ac">
        <dc:Bounds x="1092" y="300" width="36" height="36" />
        <bpmndi:BPMNLabel>
          <dc:Bounds x="1073" y="283" width="74" height="14" />
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_1ts1677_di" bpmnElement="Flow_1ts1677">
        <di:waypoint x="1380" y="248" />
        <di:waypoint x="1380" y="318" />
        <di:waypoint x="1238" y="318" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0b4i0dt_di" bpmnElement="Flow_0b4i0dt">
        <di:waypoint x="1202" y="318" />
        <di:waypoint x="1128" y="318" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_13lht1w_di" bpmnElement="Flow_13lht1w">
        <di:waypoint x="1048" y="208" />
        <di:waypoint x="1170" y="208" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0cozu8t_di" bpmnElement="Flow_0cozu8t">
        <di:waypoint x="1270" y="208" />
        <di:waypoint x="1330" y="208" />
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>