There were various "barbarian" kits, but the BG2 barbarian class resembles the 3ed barbarian class much more than it resembles any of them, and besides if they wanted it to be a fighter kit there's no good reason for it not to be a fighter kit.

And as for the sorcerer, well, people keep saying that there's something similar in the Player's Option books and thus it shouldn't be treated as an obvious import from 3ed, but no one ever seems to have actual details.