Methods and apparatus to identify media based on watermarks across different audio streams and/or different watermarking techniques are disclosed. An example apparatus includes 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 is different than the first audio stream. The example apparatus includes a watermark analyzer to compare first media identifying information in the first watermark with second media identifying information in the second watermark. The example apparatus also includes a media detection event controller to associate the first and second watermarks with a media detection event when the first media identifying information is consistent with the second media identifying information. The example apparatus further includes a transmitter to transmit the media detection event to a data collection facility.