Here's a novel one - 3 actors win best actor for the same role.

Surely a future trivia question Billy Elliot stars dance off with Olivier award says in part:

Three teenagers who played the title role in Billy Elliot - The Musical shared a top acting prize at Britain’s premier theatre awards on Sunday, beating film star Ewan McGregor.

James Lomas, George Maguire, both 15, and Liam Mower, 13, picked up the Laurence Olivier award for best actor in a musical at a London ceremony.

The boys were unknown before they were picked from 3000 hopefuls at an open audition. They had to share the role because of the number of performances each week and the physical demands of the role.