Actually, staff hates the fact and doesn't like to have copyrights from other head makers/body makers... But, in your opinion, is it possible? Staff cannot remember each head uploaded as it is or who have uploaded it first, so basically head/custom stealing is legal, but staff disagree with it.
This might clear it:

Hello Johnaudi,

I understand your concerns, I am also against copying customs, but as stated in our FAQ room for customs, we simply don't have an efficient way of enforcing that rule. There are thousands of customs and we receive hundreds per day. There is no way we can check each upload to see if they're a duplicate.

Regards,

Street (Player Relations)