Creative Mode Item Duplication into hotbar

I was pulling items from the creative inventory to fill chests for making fireworks. When I filled up the survival inventory and exited out, to store them in the chest, I had an item duplicated in the hot bar.

What I expected to happen was...:
there to be a full survival inventory and nothing in the hot bar when I opened the chest.

What actually happened was...:
I had a full survival inventory with a duplicate of the item in the hot bar.

Steps to Reproduce:
1. Open up creative inventory and put any item(I tried it with quite a few items) in your hot bar.
2. Switch to the survival inventory by clicking the chest icon
3. Move the item(s) from the hot bar to the survival inventory
4. Exit out of your inventory.
5. Open a chest
6. There should be a duplicate of the item, that you placed into the survival inventory, in your hot bar.

Notes:
-Moving a block in any direction after exiting from the inventory before opening a chest breaks the bug.
-Where you place the item in the survival inventory has no affect.
-It seems to only duplicate the first item moved from the hot bar to the survival inventory. For example, move a stack of diamonds then a stack of gunpowder to the inventory and only the diamonds will duplicate.
-The location of the item on the hot bar before moving it to the inventory also has no affect.
-Shift clicking or dragging still produces the same bug.
-I know there are other bugs reported for duplicating but they all required repeatedly pushing buttons.

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(Old 1.5) code analysis by Markku: link