>>714245034Sega of America's audio team originally wanted to do the soundtrack for Sonic 2, but Sega said they didn't like the music they showed them and rejected the proposal.
Then, when it came to Sonic CD, the audio team basically just did it themselves and put it in without asking so they couldn't get rejected again.
Naoto Ohshima, the director of Sonic CD, said he wasn't even aware of the changed audio overseas until years after the game's release.