create fabric latest build , just dropped copper sheet in mill and it got duped can anyone confirm?

Fixed by #256?

That appears to have fixed it!

cant reproduce in another world , idk maybe a world related issue

I've just encountered this in my playthrough, and it seems that the mill pulls items thrown onto it into its inventory without removing them from the world. I was able to replicate on two separate singleplayer worlds
https://youtu.be/lfL7b3ds5Y4