I think I got the major ones. Other canidates included Best Actor/Screenwriter for the 49th Oscars (Network beat both Rocky and Taxi Driver), 1981 where Chariots of Fire beat Indiana Jones and the Raiders of the Lost Arc, and 1993, where Schindler's Lost lost both acting awards.
What do the rest of you think? Did I snub anyone myself?
What do the rest of you think? Did I snub anyone myself?