Since 1.9 when holding shears in both hands and right clicking a sheep to shear it, both items will take damage. However, when removing the item from the left hand the durability resets to what it should be. If the item durability runs out it, the item in the off hand's quantity will be set to 0 and when I right click again the durability on the item will get back the durability it's supposed to have. If I break any blocks such as leaves, the bug doesn't occur. If I quit while I have the bugged item in my off hand, the item will go back to the durability it's supposed to have when I join the world again.