Oh, I agree, not carbon copies - but similar. I have the feeling that pre-I Rimmer would have gotten along quite well if he had bunked with Burns.

Yes, that's the big difference between the two, IMO; Rimmer was in a situation where he improved, but Burns wasn't. I think that the very structure of the army aided and abetted Burns's negative traits - all along, not just the promotion at the end. He could look to it as an authority on Right And Good that he could hold up to show that Pierce wasn't. Rimmer lost that, as there was no JMC or Space Corps anymore, despite his trying to hold to their dictates anyway.