I told him what we were discussing and he agrees with me that there is no alternate universe with another me. He said "you would have to believe in fate or destiny to believe that".
You can tell him that, if it is assumed that there are infinite subverses, each with a finite amount of information, he is 100% incorrect and can be proven to be incorrect with a fairly simple mathematical proof.
And he says you would have to believe both universes started off the exact same way and with the exact same molecules and atoms which they wouldn't because each universe is different.
He is also wrong about that. While the universe may be deterministic, it is also chaotic. What this means is that two subverses with identical starting states may not share all future states (due to quantum uncertainty), and two subverses with different initial states may display identical states later in their futures.
And lets say Adam and Eve are my first ancestors. Are you suggesting that there is another universe where another adam and eve meet, and their kids meet the same partners and so on down the line until you are born?
I am not suggesting there are ONE or TWO such universes, but actually an INFINITE NUMBER of such universes.