If you have 64 ingots on the slot 1 of the hotbar and you press 1 on the ingot of you've smelted , you will duplicate the XP!
MC-21793
You gain much more XP if you have 64 iron or gold ingots on slot 1 on hotbar and on furnace pressing 1 on the ingot will duplicate the XP
Resolved
Cannot Reproduce
0
Unable to reproduce, getting same amount of xp.