Ender Chest gives obsidian and the chest when using Silk Touch (Duplication)

Hi! I've uncovered a duplication glitch of sorts. When you break an ender chest with a silk touch pick, you get the Ender Chest and the 8 obsidian back, as you would with a fortune pick. This is a dupe glitch, as I can sit there and farm obsidian just by breaking and replacing the chest. I have uploaded a private video to YouTube showing it off. Here is the link: https://youtu.be/nb2Rjx1glMg