# Minesweeper confusion

I'm getting a bit confused about something I keep encountering when playing minesweeper. I keep seeing the following formation:

?????
?1x1?
?1x1?
?????


Surely those 1's should be 2's, as each one is adjacent to both of the mines in the centre? My initial thought was that this is a bug, but I've encountered it on multiple website versions of minesweeper. Am I missing something, or is this just a common shared bug?