With the multiverse all things are possible. The “mirror” universe could just be whatever multiverse happens to be the antipode of the current zeitgeist. Like a sociological dipole. Therefore appearing to be “recreated” as a psycho-re-active kind of place, but also a physical reality that always existed. This could be happening often enough through various combinations that the “mirror” universe would even have a memory of previous encounters with a “prime” universe similar to, but not necessarily identical to, the prime universe we are currently watching.
With the multiverse all things are possible. The “mirror” universe could just be whatever multiverse happens to be the antipode of the current zeitgeist. Like a sociological dipole. Therefore appearing to be “recreated” as a psycho-re-active kind of place, but also a physical reality that always existed. This could be happening often enough through various combinations that the “mirror” universe would even have a memory of previous encounters with a “prime” universe similar to, but not necessarily identical to, the prime universe we are currently watching.