I'm not sure if this is a bug or a feature. I do think it's very easy for someone to mistakenly think they're breaking down an iron block rather than an ic2 basic casing.

Modpack version (Do not use "latest")
1.53

It's intended :)

The item left in the crafting area clitch might be fixed soon, I know there has been an attempt atleast.

for some strange reason, the basic casing is often placed in the crafting terminal crafting area after shift-clicking the product of a recipe into your inventory, even when the casing is not part of the recipe you're crafting.