This may have been discussed in the past. But remember Deep Dive? Of course you do. I'm sure you remember the fight between Riku and Roxas. And Xemnas standing on the beach... And the person coming out of a rock..... Yeah, the last one I want to focus on.
When the guy comes out of the rock, we see a Heartless symbol. The person (with a creepy glowing eye) coming from the rock is supposed to be Roxas. But why does he have a Heartless symbol? He's a Nobody!?
Next, at the very end of Deep Dive we see a picture of four people. From right to left it's Xemnas, Roxas, Riku and.....Again Roxas??
Why would they put him in the picture twice? This must indicate that they are different characters. But who is this glowing guy..... Ven? Nah, long shot....
When the guy comes out of the rock, we see a Heartless symbol. The person (with a creepy glowing eye) coming from the rock is supposed to be Roxas. But why does he have a Heartless symbol? He's a Nobody!?

Next, at the very end of Deep Dive we see a picture of four people. From right to left it's Xemnas, Roxas, Riku and.....Again Roxas??

Why would they put him in the picture twice? This must indicate that they are different characters. But who is this glowing guy..... Ven? Nah, long shot....