Client-side edited mob head glitch in multiplayer

Similar to the old glitch with multiplayer signs where if you broke them but weren't allowed to, it would erase the words on the side client-side only.
If you break an edited mob head but aren't allowed to, it changes to the head that was edited. Simply hitting the head once fixes it.
Example:
A skeleton skull had been edited to look like a player's head. I broke said skull with my fist, but wasn't allowed to destroy blocks in the area I was in, and it looked like the regular skeleton skull. I punched it once and it turned back to what it was.
Sorry, Java is being derpy and I can't add screenshots. (Mac problems maybe?)