A refrigeration system comprising: at least one first compressor fluidly connected to a first suction line and a first discharge line; at least one second compressor fluidly connected to a second suction line and a second discharge line, the second suction line being fluidly connected to the first discharge line; a condenser configured to receive refrigerant from the at least one second compressor; a first evaporator configured to receive refrigerant from the condenser and discharge refrigerant to the first suction line; a second evaporator configured to receive refrigerant from the condenser and discharge refrigerant to the second suction line; a first refrigeration case configured to be cooled by the first evaporator within a first temperature range or a second temperature range, the first temperature range being lower than the second temperature range; a second refrigeration case configured to be cooled by the second evaporator within the second temperature range; a bypass valve disposed between the first evaporator and the first suction line; and a controller configured to: cool the first refrigeration case within the first temperature range by operating the at least one first compressor and moving the bypass valve to a first position in which the first suction line receives refrigerant from the first evaporator, and cool the first refrigeration case within the second temperature range by stopping operation of the at least one first compressor and moving the bypass valve to a second position in which the second suction line receives refrigerant from the first evaporator and the at least one first compressor is bypassed. at least one first compressor fluidly connected to a first suction line and a first discharge line; at least one second compressor fluidly connected to a second suction line and a second discharge line, the second suction line being fluidly connected to the first discharge line; a condenser configured to receive refrigerant from the at least one second compressor; a first evaporator configured to receive refrigerant from the condenser and discharge refrigerant to the first suction line; a second evaporator configured to receive refrigerant from the condenser and discharge refrigerant to the second suction line; a first refrigeration case configured to be cooled by the first evaporator within a first temperature range or a second temperature range, the first temperature range being lower than the second temperature range; a second refrigeration case configured to be cooled by the second evaporator within the second temperature range; a bypass valve disposed between the first evaporator and the first suction line; and a controller configured to: cool the first refrigeration case within the first temperature range by operating the at least one first compressor and moving the bypass valve to a first position in which the first suction line receives refrigerant from the first evaporator, and cool the first refrigeration case within the second temperature range by stopping operation of the at least one first compressor and moving the bypass valve to a second position in which the second suction line receives refrigerant from the first evaporator and the at least one first compressor is bypassed. cool the first refrigeration case within the first temperature range by operating the at least one first compressor and moving the bypass valve to a first position in which the first suction line receives refrigerant from the first evaporator, and cool the first refrigeration case within the second temperature range by stopping operation of the at least one first compressor and moving the bypass valve to a second position in which the second suction line receives refrigerant from the first evaporator and the at least one first compressor is bypassed. <EOS>