B A in A's reality, B in A's reality, A in B's reality in ....

[porton]

TL;DR

Do we produce an infinite number of realities this way?

I read somewhere in Quanta magazine that (if I understood correctly):

When A and B watch C, then C in A's reality may be different than C in B's reality (as B is seen by A?)

What if A and B watch each other? We could make chain: A in A's reality, B in A's reality, A in B's reality in A's reality, B in A's reality in B's reality in A's reality, ...

So do we this way obtain an infinite set of different realities?

 

[Nugatory]

So do we this way obtain an infinite set of different realities?

No, but we do obtain a powerful argument against trying to understand quantum mechanics by reading Quanta magazine.

And kidding aside... you’re describing a variation of an old paradox called “Wigner’s Friend”. Google will find much more about this class of problems.