The Bug

When in creative mode a pressing q and a hotbar number button at the same time you have a chance to desync the item. Proceding to pick up the desynced items and opening a chest will result in the desynced items becoming what they were desynced to

The video of the issue

https://youtu.be/uY9k3zKdkYs

How to reproduce

1. Get a chest and place it.
2. Get a item you want to dupe.
3. Place it in a hotbar slot.
4. Place one dirt in a hotbar slot.
5. Press Q and the slot of the dirt.
6. Do it some times.
7. Open the chest and you have duped the items.