Yeah, they should be equal in battle. Roxas did actually win from sora though, IMO he actually won the fight when he pointed the Oblivion in his face. If you would fade out black after Roxas did that, it would seem as if he had won.
He could have finished him off there, actually, but he didn't. I mean, Roxas wouldn't have done that, even if Sora wouldn't have summonned his Keyblade and slashed him. I think (as someone pointed out before) Roxas was testing Sora, because he's asking him why the Keyblade chose him, the "You make a good other" stuff etc. And yes, it would be awesome if Sora and Roxas would be holding their keys in each other's face and that the battle would have ended in a draw, that would have made more sense IMO.