Although it may not necessarily be possible if playing Minecraft legit, it did cause problems for me as I was building my map in Creative (Mainly filling up my entire inventory space with leather armour.)
It is also something that shouldn't happen. When you craft 64 Dyed Helmets, you should get 64, not over 1000... I, myself, would still consider this to be a bug.
The exact same thing also happens with every other piece of Leather Armour, and even in Survival Mode.
I have also noticed this. Just created a Superflat world and not an animal in sight!
I understand, but it is still interesting nonetheless!