This bug only occur on recent update 0.14.2 .

When Im helping my friend after the update via lan game and I joined his world, while Im harvesting some tree or going mining Im shock that some of my tools went missing but then I realise that my item is duplicating I was happy at first but I realised when Im looking in my inventory that the missing tools/item are replaced by item/tools that are duplicating. Please look into this matter. It never occur on 0.14.1

It only happen when Im only joining my friend some survival world via lan game. But when I test it when Im on my own world survival mode, it didnt occur yet and I hope it not occur.

I didnt try it on server yet.