Hm. To simplify, it's akin to how a Palace is laid over a real-world location, except in this case, it's multiple 'real-world' Leblancs. Probably a result of the slightly differing cognitions of the various 'us' who might be expecting different things from it.

[He's still holding the door open, casually.]

I have some skill at manipulating that kind of thing, so I picked an empty one. It might not be yours or mine, but hopefully Sakura-san's coffee is universal.