Picking up an item has a chance to duplicate it

I am also having this issue.
Windows 10, full Minecraft, having issue with dirt and wood.

Also happens, was mining coal when it happened.

happens with sulker boxes too...
It happened in xisumavoid's update video on youtube but with wood.

gif of bug in action

I was able to re-produce this bug by simply throwing stacks of items to the ground, in my tests it happens rarely for small amounts of stacks but the more you throw down the more likely it is to happen.

A video of the bug: https://youtu.be/vZGfwCFMwuE?t=1m59s

Marcono1234 MC-115404 explains the bug, and has a video.

Confirmed for official 1.12.

@@unknown could you please attach a video showing this bug and exactly describe what you are doing to reproduce this since it is supposed to be fixed.

I had this happen in official 1.12 as well now. I broke a shulker box, picked it up, and left the area. When I came back later, a shulker box was in the place of the one that I broke, and had the exact same items in it.

On second thought, create a new issue; since a fix was attempted for this, and you're experiencing it only on reloading chunks, it's probably different.