Watch out with those sealed ps2 games, there are some late reprints around from those hard to find games.
You are right, However hack mutation part 3 if there was a reprint out there there would be massive amount like all the other examples also the price would be pretty low.
A UK versions or even any other versions are not readily available, even used they sell for 50 -60 euro's sealed 100+ for the UKV. Other versions are 50% the price aside that this copy had costed me nothing anyways.
Examples of massive reprinted games in PAL region:
Persona 4
Street fighter alpha anthology
Shin megami tensei digital devil saga part 1 and two
okami
etc etc
This one is not on that list if it was the prices would be really low like the others mentioned above.
Persona 4 is still 20+ euro's but only because the game is really sought after but it has received many reprints.
Especially the shin megami tensei digital devil saga games tanked in price those were really expensive games wich are now only 10 - 15 euro's or less even sealed. Devil summoner vs the soulles army however remains rare and without a reprint.
Also I do know that reprints come with a lighter box, and you can check the packaging if the release date matches the box. if It's a reprint the year will be some years later than It's original release and in some cases different rating system etc. Also slightly alternate colour
If you open it you can also see the chance of date on the manual and the disc.