Const. Erin Cooper told CBC News that the first crash occurred just after 10 p.m. ET on Saturday at South Service Road and Crediton Parkway.
The single-vehicle collision killed a Mississauga man who was driving a Honda Civic. The 31-year-old driver of the vehicle was pronounced dead at the scene.
Hours later, a motorcyclist was killed in a single-vehicle crash at Burnhamthorpe Road and South Millway.
Cooper said the 22-year-old male victim was transported to hospital, where he later died.
Both crashes remain under investigation, Cooper said.