Rotary Couplers?

Yes, these are rotary couplers. Here you can see the brake pipe is on the "wrong" side of the draft gear. When these cars are coupled for rotary dump operation, the brake pipe is on the right side of the cars (when viewed from the B end). The brake pipe can be cut in or out at each car from one side of the train and it can remain continuously connected throughout the dump phase. In this photo, two rotary ends are coupled together so the brake pipe crosses underneath the couplers.

Someone needs to take a picture with two couplers rotated upside down on two coupled rotary end hoppers.

I suppose that could happen, but they don't rotate freely. If two cars were coupled up this way and one was dumped, I suspect then the couplers would be out of alignment. But unless the cars are going to be set up for rotary dump operation, there is no effort taken to ensure all the cars are connected A-end to B-end. An A-end to A-end coupling like this is very common.