The thing is, I don't think the other Keyblades are canon. That's just how video games work. In Resident Evil, when you get bit by a zombie during gameplay, why don't you turn into a zombie? Because it's not part of the storyline. Things like that in gameplay have to be taken with a grain of salt. Sora goes from start to finish with the Kingdom Key, the other Keyblades don't exist. It's just gameplay. Frankly, I don't care for the other Keyblades and plan to play the entire game with the Kingdom Key which is the one true Keyblade (not to mention Riku/Ansem's "Darkblade", Mickey's Keyblade, Roxas's Oathkeeper and Oblivion, and whatever else pops up in there).