I've noticed on my lvl 51 Nord warrior, i can wear 2 heavy helmets at the same time.
I've got superior ebony helm.. enchanted with stuff and i can also equip a Falmer helmet, i can equip that falmer helm with any other aswell so it's not just 1 particular combo. They're both classed as heavy so i've got no idea how's it possible, glitch or what?