The piston rings are an oddity - it requires (3) per leg, and according the the BMW dealer inventory system, they charge you by the ring. Yet, they are indeed packaged 3 rings per packet. So, when they sent you 6 packets, they never bothered to look at the contents. I've wondered if the pricing is actually supposed to be per packet, instead of per ring, because of how they are packaged - and how expensive it gets to buy 6 rings.
My original rings are still oval in cross section - the new ones are actually a little bit more square-looking in cross section for some reason - the opposite of what Georges observed. Hmmm.