This morning I bought a used copy of Mega Man Xtreme. I'm in the UK, but the game box has a ESRB rating on, a part # of DMG P BM6E, and the cart is DMG BM6E USA, so my question is - is this a US import, or is this how they were sold in the UK/Europe?
Yeah that happens sometimes. Over here we had European Neo Geo Pocket games and some Japanese DS games were imported by Best Buy and others. Usually it's just imported stock, much like how North American Atari 2600 games ended up being sold overseas.