I wanted to know if these are actual beatmania songs:

[TTRlovesMittens]

Are Koibito ga Santa Claus and Naze... actual BM songs? They're on BM GB Gotcha Mix 2. I wanted to know if there are actual versions of these songs on BM, or if they were just licenses for the game?

[dj Outlaw]

According to the OSTs of the Arcade 5 key series, no it doesn't look like it.

From what I remember, both of the Gotchamixes had unique licenses that didn't ever appear in AC beatmania (Automatic, Cruel Angel's Thesis).