It isn't something that happens often, a university and pro football game in the same stadium on the same day. In 2005, a doubleheader occurred in Hamilton — McMaster played rival Western in the afternoon at Ivor Wynne prior to a night game between the Tiger-Cats and Calgary Stampeders.
It also happened in 2002, but it wasn't planned — a few months before the season, some Internet geek looked over the OUA and CFL schedules and saw that a Queen's-Ottawa Gee-Gees and Toronto-Ottawa game were each scheduled for the afternoon.
The university game ended up being moved to the evening; the Ottawa teams lost both games.
(Hat tip to Robert Hilson on the Hamilton footnote.)