In a secret laboratory hidden in some unknown place, an experiment is carried out trying to open a passage that would allow traveling to parallel worlds, but the experiment goes terribly wrong.
An accident happens during the experiment, which breaks the boundaries between several parallel worlds at once for a fraction of a second. because of this, the inhabitants of these parallel worlds were randomly redistributed among the affected worlds, and it is not rare that more than one version of the same person ends up in the same world. For people everything happened normally until there was a sudden flash and a noise that resembled thunder, but when the flash disappeared they were already in a different world where theirs were different physiologically and culturally,
Only 5% of people were lucky enough to remain in their home worlds, which may not make things any easier when receiving people from parallel worlds to theirs.