Throwing potions / throwable projectiles causes both hands to bob up and down

If you place a throwable item (such as a potion) in either your mainhand or offhand and hold an item with your other hand, throwing the potion causes both hands to bob up and down. This only happens when throwing potions in Creative mode, but also occurs with snowballs, eggs, and Ender Pearls in Survival and Adventure mode.

The hand that throws the potion makes the bobbing animation slightly before the other hand.