Okay, first I need to say that I'm one of those people that once I put furniture in place, I like it to stay there. It's just one of my quirks.
With that said, if a guest were to place two beds together, I don't think that would bother me as long as 1) the floor wasn't scratched and 2) they put the beds back at the end of their stay.
Taffy, I think your friends are very comfortable with you and feel welcome with you and your hospitality. They probably would feel bad if they knew that it irritated (?) you to have the beds moved.
I hope they have been putting the beds back at the end of their stay.
You are entitled to feel the way you do, doesn't make it right or wrong. I'm such a help aren't I.