But what about cases where the other side looks the same as yours?
Let's go back to the infinite worlds concept. A new one is made every time something happens that could've happened differently. For instance, if I rolled a six-sided die and got a three, there would be five new worlds where a different number came up. And another where I didn't roll a die at all, and so on. Everything in these new worlds would be the same as the world they spawned from up until the point where I rolled the die.
Now what if there was a window, a natural window, that appeared without my noticing it shortly after I rolled the die? What if I turned and walked right through it, and I thought I was still in my own world? (For argument's sake we'll say that on the other side the me that was in the room of the new world had already left by this point.) What if I was walking around in a whole new world, but I didn't know it, because everything was the same except the number I rolled?
Anyway, I know there are lots of holes in this theory (like daemons getting sick and me meeting myself, etc) and it's just the beginning of a bigger concept, but I'd like to get everyone's thoughts on it anyway.

(And as for the poll question, that's assuming Xaphania hadn't closed all the windows.)