Placing 4 Sticky Pistons, all in the same direction, and having Redstone in a 2x4 behind it and it "on" will only allow the 2 side pistons to work, the middle 2 pistons won't even budge. (All shown in the photos included)

Also, the world I used to find these bugs is in the attachments. The bug was found in the large building also shown in one of the photos.