I know this was an old bug quite a long time ago, but it just happened in my new game.
I was constructing my first building, a dining hall, and when trying to place two tables, both hearthlings carrying them got stuck side by side on two already placed chairs. 
They stayed there for a very long time, which isn’t very good at the beginning of the game.
Here’s a screenshot:
I know that I can just work around this by not putting the furniture and decorations when building, but I do prefer to do so.