As far as I can tell, you can prove
that the number of configurations in a finite universe is always finite. Out universe is expanding towards infinity, but currently is finite in size.
As we observe a finite universe, this does suggest that a multiverse as such does not exist. A limiting factor on the size of the observable universe would also apply to such a theoretical multiverse.
A multiverse would have limits to it's size and expansion also. As far as we can currently observe, while the things such as quantum superposition have no known upper bounds on size, I would assume, like the visible universe they are also limited.
So I only expect that we will find possible different trajectories or energy states of a particle, not an entire "Evil Universe" Starship Enterprise. Now while such a claim is ludicrous, the concept of a full scale multiverse would suggest such things do exist... so rather problematic should someone observe that there is no limit, and all possible universes exist!