If you're really interested in this kind of stuff, this is a really good/eye-opening read
http://vgmdb.net/forums/showthread.php?t=11231
Tangential, but I'll say very cryptically that a particular percussion loop is used in both Kingdom Hearts and D4: Dark Dreams Don't Die. Cracked me up when I recognized it.
I've browsed through a good deal of AKAI libraries myself years ago so I'm very prone to recognizing how common it is for soundtracks. Much like visual artists tracing, it usually comes down to a lack of time allocated to them by their clients. In Command & Conquer Generals for instance it's pretty much just the USA faction which has actual fully original compositions, whereas the other two factions China and GLA have their soundtracks almost exclusively made out of prefab loops. I don't blame the composer when he was single-handedly tasked with making basically 3 full soundtracks for 1 game.