You can duplicate items in your creative hotbar

When you Ctrl + Drop an item in your hotbar while holding an item in your cursor you duplicate the item instead of dropping the item in your hotbar.

Steps to reproduce:

1. Place an item in your hotbar
2. Grab another item in your cursor slot
3. Place your cursor over the item in any except for the 'Search Items' and 'Survival Inventory' tab.
4. Press the Ctrl + Drop key (usually Q)

Observed Behavior:

You drop and duplicate the item in your hotbar.

Expected Behavior:

The item in your hotbar gets dropped and disappears.