Kingdom Hearts 2 question?

Roxas never actually left Sora. Remember how Donald and Goofy didn't see Roxas. Sora fought Roxas in the place you appear in at the beginning of each game, which is a place inside Sora's heart. That's why everything related to the Keyblade happens there, and that's why you see the seven princesses on the floor. Sora was pulled into that place to fight. So really Sora fought Roxas inside his heart.