When placing a piston against a redstone block, if you run (or fly) towards the block whilst placing the piston at an upwards jump (or downwards fall) the piston heads will simply duplicate in both the original starting position and the players newly acquired positioning.  This does appear to only be a visual, after quitting and rejoining the world the bugged piston head disappears. The piston head, whilst a visual, does take up a block space and is completely unbreakable to the player. (NOTE: Works with both sticky and non-sticky pistons.)

This issue can be easily replicated and has accidentally occurred numerous times to me whilst playing with redstone features in the new snapshot.

Short Recreation of Bug: https://youtu.be/2oOwaqBnnwU