In the Canadian provinces and territories of Alberta, Newfoundland and Labrador, the Northwest Territories, Nova Scotia, Nunavut, Prince Edward Island, Quebec, Saskatchewan, and Yukon, licence plates are currently only required on the rear of the vehicle. The remaining provinces, British Columbia, Manitoba, New Brunswick, and Ontario, require the licence plates to be mounted on both the front and rear of the vehicle. Dealership plate frames or custom plate frames are allowed as long as the frame does not obstruct view of validation stickers or district.

Can we conclude that do you have to have two license plates in ontario?
yes