Odd armor behavior

I was not going to post this because I used an NBT editor to do this, however, I realized that the glitch was not caused by the NBT editor and thus posted it anyway.

So I NBT edited armor onto myself. Only problem is, I accidentally put it on upside-down. I took off the armor, only to fill my inventory with phantom helmets. This happened because when I took the armor off, it dropped on the ground with an amount count of 0. These phantom helmets filled my inventory, as shown by my NBT editor.