SirPrimalform: Well they mostly started ignoring continuity from series 3 onwards anyway (the text at the beginning of Backwards hardly counts). :P Anyway, I was just suggesting that given his personality this is a hologram of the resurrected and now dead Rimmer rather than the one from the mirror universe.
Well, Rimmer died with the rest of the Red Dwarf crew (except for Lister who was in Stasis) in the Cadmium II accident, all because he failed to fit a drive plate correctly.
He then changed history in Timeslides and was therefore alive at the end of that episode, albeit only for a few moments as he was then killed in an explosion.
Then when Kryten's nanobots rebuilt Red Dwarf and the crew he was effectively resurrected (well, technically a clone as it was a copy of the original Rimmer and the crew).
And now he is a hologram, so somewhere he died yet again!