Does Sora remember Namine in Kingdom Hearts 2

No he does not. This is obvious in the first scene we see Sora where he is confused about the entry in the journal to "thank Namine." None of the characters understand why they need to think her. Now, some may speculate that Roxas being a part of Sora would remember her because of his interaction with Namine during the prologue. However, this can be contradicted by the fact that the Twilight Town in the prologue is not the real Twilight Town. It is a computer re-creation of the town. All of the events that occur in the town really did happen, but it was used as a way to show Sora's memories being rebuilt from another side. Because, if Sora lost his memories, then Roxas would have lost his because they are two sides to one coin. The prologue was an interesting way to show the rebuilding of Sora's memories while giving us a new character to connect with and grow to appreciate.