There is a duplication glitch when you enchant a sword 3 times with an anvil. It happens when you use Sharpness V, Fire Aspect II, Knock-back II. To replicate it, place an anvil then enter the anvil menu. shift click the sword from your hotbar into the anvil then shift click Sharpness V. Then Fire Aspect II, Then Knock-Back II. The sword should duplicate when you pick it up out of the result box into the first box. This only happens on a server. It should look like the picture.