This had been guessed at years ago in DC Comics when Superman would try to go into the past and change things, only to find that he went into a parallel universe. The DC editors even maintained that in an infinite universe, there would be a few with a REAL Superman where their stories actually happened. The 50's through '80's Superman was earth-1, the golden age Saperman was on earth-2. We live on earth-prime. More earths were made for Captain Marvel, Quality comics heroes and various rogue superheroes.
There was also a scifi short story where people found out about this and started killing themselves because somewhere else another version of them did not make the same stupid mistakes.
Frankly, there are severe metaphysical problems with this approach. Stanley Jaki deals with this in "Is there a multiverse?" I am sure there are better treatises that show the theory to be absurd.
Here are some archiv.org links to articles about the multiverse:
"I am sure there are better treatises that show the theory to be absurd."
It does seem crazy, doesn't it? As crazy as invisible men in the sky, though? Hmmmm. To each his (many) own, I guess.
"All the Myriad Ways" by Larry Niven.
The story involves the discovery of parallel universes where a universe is created every time someone makes a decision. Wheat bread or rye for your sandwich? Parallel universe created right there: one where you had wheat bread and another where you choose rye. The realization that such universes are created for each decision robs a large segment of the population from the belief in right and wrong. After all if you agonize over this moral choice, what good does it do you? A parallel version of yourself will make the exact opposite choice. So there is no right or wrong. Everything will occur anyway. So, given that, why not do whatever you want? Or why not think about killing yourself and in so pondering the question, another parallel universe is created in which you actually do the deed.