When I saw the title of this thread I immediate thought of the counter rotating props ala Shackleton, where each engine drives two props, one clockwise, the other counter clockwise. I have always wondered about the efficiency of such an arrangement and the gearbox complications (and the power losses) involved.
I assume in a twin engine aircraft where one engine direction differs to the other, it makes a difference which one is turning which way. It certainly has an effect on stability in twin engined boats.