One of the movies that stormed my senses so hard was the one with Jet Li entitled "The One"(the other perhaps is "Star Gate") that talks about him being an officer of a multiverse authority agency that polices interdimensional travel via wormhole, seeking to hunt down all variations of himself in alternate universes. But now, there are many of these multiverse science fiction stories being made, motion picture or comic books-wise.
In quantum mechanics, a particle’s property is defined by a wavefunction, and that function changes over time. While measurable data is a real thing and wavefunction is another, in our understanding of Many Worlds Theory, the wavefunction is definitely real, and so every time a “quantum decision” can be made, every quantum possibility happens somewhere, and what we experience in our universe is simply a path being chosen by one of these plurality of quantum possibilities. And if we want to be strictly mathematical about it, the cosmic inflation(10 to the negative 30th seconds) could have also produced 10 to the 10th to the 90th more or less worth of identical space, time and matter for it to happen.
However the many-worlds-interpretation doesn’t require that Parallel Universes are real. The Parallel Universes are, in a conservative view, is simply just a visualization of what the wavefunction creates.
But there are some physicists who are putting together the huge amount of universe-spacetime created via eternal inflation and the many-worlds-interpretation model/effort to argue that Parallel Universes are real, and that for every "quantum realization" that occurs in our universe, there exists a real Parallel Universe where everything that ever occurred in our universe occurred also over there, except for that one difference.