When you mine Sand in water with the Mining Gadget, it gets duped.Haven't tried Gravel yet but I guess it's related to gravity blocks. Still works using the latest 1.15.2 version of Mining Gadgets.

Edit : Gravel doesn't work?

Can't reproduce. What upgrades did you have on the gadget?

Please update this issue if you have found a way to reproduce this issue, thanks 👍