I noticed it after trying to place the ocean barn and had to back out of it to go cut down some seaweed to make space, but I don't know if that's when it appeared. I wouldn't mind the free machines, but it duplicated an entire chest of milk pails and shears that were from some other bug duplicating them when I upgraded my chicken coop, and now I have two entire chests of milk pails and shears that I can't get rid of because you can't sell or trash them.
I play on Steam/PC/Keyboard & Mouse
Game Version v1.1-1222
Pictures of issue and game save attached