DJ Hero is a game developed by FreeStyleGames and published by Activision. While the game incorporates many well-known DJS, such as 2009 DJ of the Year DJ Z-Trip, DJ AM, Daft Punk, and DJ Shadow, many of the remixes were done by an in-house remix team at FreeStyleGames.
Check this link, http://www.djhero.com/music , to properly label the mixes that were done by actual artists and NOT by DJ Hero’s in-house remix team.