Anvil Duplication Exploit

Orange = Reproduce

Red = Visual

Purple = All

Green = Expected Results

 

In my friend's world they have a thing that dupes anvils, and it looks like this:
-D = Big Dripleaf

-R = Redstone Torch

-A = Anvil

Im not sure which way it is facing but i know their seed is the Coastal Village and the long side is facing the same way as the direction to the village from the spawn island.

  DDDDD

DRRRARD

  DDDDD

DRRRRRD

  DDDDD

 

Basically, they have a tall stack of anvils for some reason from A, from their demonstration they broke the one that is one layer above the diagram and placed it on the dripleaf directly above it in the diagram, then they placed on the second Dripleaf at the bottom of the diagram and began to glitch between the one they placed it on and the Dripleaf directly above it then they saved and quitted then went back in and there was an anvil on the floor as an item and another one not glitching out as a Block on top of the dripleafs.

I don't know how they found this exploit but I think they said YouTube, but I cannot find anything on it anywhere.