That's not what I was talking about though, I was talking about the perspective of the root. Obviously once you already are in a branch there is a fact as to whether you are in that branch, even if you can't tell yourself.

But the Anthropic Trilemma scenario we're discussing explicitly postulates this: that physically separate but identical copies of my body will be constructed, have identical experiences for a while, and then diverge.

Not as far as I can tell. The first experience after being copied is either winning the lottery or not.