I was going to make this a poll but goofed up somewhere, as I didn't get its input screen even though poll was checked (maybe because I didn't preview first).
And the more I watch Mirror, Mirror the more I toy with the idea that the Halkans
were somehow controlling the whole thing as a test.
Its always puzzled me why the Halkans arent evil in the mirror universe, maybe your speculation is in fact the reason.
They were controlling it from the beginning