Josh: What is the name of the white and blue semi that Optimus Prime gives the Matrix to in the movie?
Buck: Ultra Magnus.
Josh: Would you tell Six that he was a different robot, not another Prime.
Buck: Tell him that in the comics they're brothers. That's why they look alike.
Josh: I'll tell him. He told me Rodimus was after Prime and that Ultra Magnus was just an upgraded Prime. And I said oh no no, Buck and I have watched that way too many times.
Buck: Damn straight.
To be fair, when you remove his armor Ultra Magnus is basically a re-painted Optimus Prime, so I can see how our pal got confused:
Does Buck know way too much about Transformers?
C. But he didn't mention how Ultra Magnus appears in the Japanese continuity!