Example methods disclosed herein to identify media sources include determining whether a first time difference between a first meter signature and a second meter signature associated with presented media is equivalent to a second time difference between a first reference signature determined to match the first meter signature and a second reference signature determined to match the second meter signature, the first and second reference signatures being associated with a first one of a plurality of media sources. Such example methods also include, in response to determining that the first time difference and the second time difference are equivalent, appending the second reference signature to a first tracking segment associated with the first one of the media sources to cause a first time length associated with the first tracking segment to be increased based on at least a respective timestamp associated with the second reference signature.