It was well known before that the Para Para US Mix was different from the first Para Para MAX, despite having essentially the same CD jacket. Geneon was unable to secure worldwide rights for some tracks in the original, so they substituted a few. But I had no idea just how many (more than half, actually). And the "new" ones are quite good, on average.
Somewhat ironically, this information came to my attention only due to the endless quest for legality. By now I have three CDs: a CD-R of mysterious origin, a Taiwanese knock-off (a present from the family, tired from my whining about not being able to find the CD: I'm sure they had best intentions), and the aforementioned U.S. mix. The result is, I still miss some tracks.