^^^
And, based on what we saw in TNG's Parallels, all of those "Mirror Universe" continutities could very well exist. After all, in that episode we learned there are at least 285,000 realities out there. There might well be at least a few variations of the Mirror universe aside from the one established in TOS and followed up on in DSN.
(In fact if you feel the need to shoehorn in the various novels, comics, games, fan-film, cereal boxes and whatever that have explored Trek in various ways, that TNG episode is the perfect rationalization: they all exist! They're all valid. Problem solved.