Windows 10 (I don't know my java version, not like it matters.)
In the inventory as well as on armor stands, if Player Heads have a second layer, the layer renders below the head's texture while they should be appearing directly over the head. When placed down in certain angles, the second texture also inverts and tilts.
(An earlier version said it was just fine – I was mistaken.)
MC-140930 Hat layer on player heads is offset