Tbh, I had the same thought about the face. But climbing out of a tomb is a cool entrance.
Pyg knows who is who. Or Hurt, who he is most likely working with, knows at least. Dollotrobin announces himself as Damian Wayne.
Pyg makes drugs that mess with your identity/ego. Deathwing had a dose of it on his blade. When he cuts Dick, he drugs him.
I don't think that the Robin Dollotron comes out of nowhere. The issue is about *cough* dark mirrors of themselves. It's also interesting that the Robin dollotron is defective - which is once again tying into Damians insecurities.