Star Trek franchise has concepts of parallel (or alternate) universes/realities. So does StarGate (in some SG1 episodes).
Is there any mention of such a concept as parallel universes in Star Wars canon?
The question is restricted to G,T, C and at the worst case S-canon.
Also, the general handwavy "always in motion, the future is" is not what I have in mind – I mean an actual specific parallel universe, somewhat or completely different from "main" one, being mentioned as part of the plot.