Villager trading dupes emeralds

I put in a stack of emeralds, trade for the full stack (shift and click). In the box before you exit, my emeralds are gone, and the math has computed right (I double checked with a calculator). but when i exit the trading box, a stack of emeralds pops out away from me as if i never used it, only slightly fewer. The new stack is re-useable. This was found in a survival mode started game, cheats activated, naturally gen village(ers). if its a map problem, it's VVVVV (5 V's).