Piston-Based Block Duplication Exploit

There's a bit of context to this one, and I haven't yet given it a test in singleplayer, but it involves an abuse of pistons that allows you to duplicate any block, including diamond blocks and the like.

I will first describe how to reproduce this bug, as it becomes fairly self-explanatory.

Effectively, you first create a pulse circuit by placing an observer and making it observe its own output in some way. Effectively run a redstone wire from the back of the observer to the front and, when the wire is placed, the observer will pick it up and send a pulse, which the observer will pick up, thus sending another pulse. This creates a very quick repeated pulse of signals that can cause massive server lag but otherwise isn't really a problem, and not the one I'm focused on here.

The problem is what happens when you connect a piston to this circuit. As you may expect, it starts extending and retracting rapidly. However, if you place a block in front of it, something strange may happen — it may duplicate the block.

I have tried this numerous times, with various blocks, and though duplication does not always occur, it is definitely a very common result.

I believe I've explained everything, but can provide more information if need be.