Flashback (1992) was inspired by Out of This World (1991, called Another World in Europe) but was not made by Eric Chahi. However, Eric and the creator of Flashback, Paul Cuisset, both worked on a game called Future Wars in 1989.
Out of This Worlds original Amiga version credits just two people: Jean-Francois Freitas who did music and sound effects, and Eric Chahi who did everything else.
Personally, I prefer the SNES Interplay port's music by Charles Deenan, but all versions of the soundtrack are good in their own way.