Yeah, Redump has a pretty good collection of PS2 games, but there are still many holes. My TimeSplitters v1.00 is one example.
Many reprints don't end up changing anything, but it's certainly a possibility. Thing is, you'd have to trust that everything is as it was originally sold if you're buying it used. I know that some people replace cases that get banged up, or even replace games that got scratched up and put it in their old case, so unless you're buying brand new copies of everything (which can also just be reseals), it's a crapshoot trying to find a specific version of a game for sale. *shrug* But we do know there's different artwork now