Okay, that's weird. One of those pistons is operating in a T-flip-flop operation (if a sticky piston is powered for one redstone tick, it will only place or retract the block, not do both operations as is intended), but the other seems to be operating in normal fashion at what I suspect may be a faster speed than it's normally supposed to be capable of. I'm not sure what causes it, but that's an interesting find.
