Punching a full Drawer with the slot that the item will go into causes it to work twice

[aaronhowser1]

Punch

I imagine its because now you're technically mining with a different item or something (first nothing, then Coal), so it punches for each of them

[aaronhowser1]

This is using StorageDrawers-1.16.3-8.2.2

[jaquadro]

This is a long-standing issue without an easy solution (it's a behavior deep in vanilla that would essentially need a coremod to solve). I believe your observation is correct.