Using middle mouse button to get an item in your inventory gifts you that said item. However if this is used on a player head, say names "Links" instead of giving you "Links's Head" you are given "Player's Head" the default steve skull. It's obnoxious to have to re-enter the name later if I want to move the skull as well as forgetting what the head was named.
You can copy the NBT if you hold CTRL 🙂