If a session has two players with the same Aspect and dreaming moon, could they get their slabs confused and die on the identical but wrong one? They'd have no way of telling them apart, but knowing Sburb it wouldn't grant an exception and they'd just be fucked over and die anyway.

Oh my god that would be the stupidest way to die and not Ascend. Again, no precedent, whether Slabs/Beds are interchangeable among an Aspect or not, is kind of never touched upon sooooo. 

In the end when it comes to 100% fanon speculation, it’s up to you.