Incredibly easy and game-breaking duplication glitch

On our realm, my friend (who plays on an iPad) can simply double-tap any item while in a beacon and it duplicates it. I know this isn't some sort of cheat or magic trick because our realm doesn't have cheats enabled and I've seen him do it in person. It's made some people quit the realm because of how it's ruined the economy and all sense of accomplishment, please fix this as soon as you can.

 

Thanks!