An apparatus comprising: a watermark detector to detect a first watermark embedded in a first audio stream associated with media and to detect a second watermark embedded in a second audio stream associated with the media, the second audio stream being different than the first audio stream; a watermark analyzer to determine whether first media identifying information in the first watermark is consistent with second media identifying information in the second watermark, wherein the first media identifying information includes a first source identifier and a first timing identifier and the second media identifying information includes a second source identifier and a second timing identifier, wherein the first media identifying information is consistent with the second media identifying information when the first source identifier matches the second source identifier and the first and second timing identifiers match an order in which the first and second watermarks were detected; a media detection event controller to associate the first and second watermarks with a media detection event (234, 316, 318, 320, 322, 324, 326, 328) when the first media identifying information is consistent with the second media identifying information; and a transmitter to transmit the media detection event (234, 316, 318, 320, 322, 324, 326, 328) to a data collection facility, wherein the watermark detector is to assign a first timestamp to the first watermark when the first watermark is detected and to assign a second timestamp to the second watermark when the second watermark is detected, the media detection event controller to associate the first and second watermarks with the media detection event (234, 316, 318, 320, 322, 324, 326, 328) when an interval between the first timestamp and the second timestamp is less than a threshold, and to disregard the first and second watermarks when the interval is greater than the threshold. a watermark detector to detect a first watermark embedded in a first audio stream associated with media and to detect a second watermark embedded in a second audio stream associated with the media, the second audio stream being different than the first audio stream; a watermark analyzer to determine whether first media identifying information in the first watermark is consistent with second media identifying information in the second watermark, wherein the first media identifying information includes a first source identifier and a first timing identifier and the second media identifying information includes a second source identifier and a second timing identifier, wherein the first media identifying information is consistent with the second media identifying information when the first source identifier matches the second source identifier and the first and second timing identifiers match an order in which the first and second watermarks were detected; a media detection event controller to associate the first and second watermarks with a media detection event (234, 316, 318, 320, 322, 324, 326, 328) when the first media identifying information is consistent with the second media identifying information; and a transmitter to transmit the media detection event (234, 316, 318, 320, 322, 324, 326, 328) to a data collection facility, wherein the watermark detector is to assign a first timestamp to the first watermark when the first watermark is detected and to assign a second timestamp to the second watermark when the second watermark is detected, the media detection event controller to associate the first and second watermarks with the media detection event (234, 316, 318, 320, 322, 324, 326, 328) when an interval between the first timestamp and the second timestamp is less than a threshold, and to disregard the first and second watermarks when the interval is greater than the threshold.