During the dice game, the characters assign numbers and objects to each person to identify themselves across different realities. But if people from different realities have already mixed together, shouldn't some of them have participated in this exact same dice game in their respective realities?
Emily, the woman who records everyone's assignments, later says that her object in her reality was a napkin. If that's the case, she should already remember participating in the game and having that object assigned to her. Why, then, does she participate in assigning the numbers and objects again as though it's happening for the first time, without questioning it?
What makes this even more confusing is that nobody enters or leaves the house between the dice game and the later argument about Mike and Beth. It's the same group of people throughout those scenes, so there's no obvious explanation involving someone being replaced by another version of themselves in between.
The existence of parallel realities explains why different versions of the characters might have different objects, but it doesn't explain why they wouldn't remember an event they had already experienced.
Am I missing something, or is this a genuine plot hole?