It is not a canard. When I was heading to Europe in 1973 I took the train across Canada to Montreal. I met a group of six Americans who heading over as well. They were busy sewing Canadian Maple Leafs on their back packs. Being a naive teenager, I was shocked that someone was so ashamed of their country's policies that they had to conceal their identity. They assured me that the practise was quite common. 

Not sure if it is in business still, but there was a company that advertised phoney covers for American passports that made them look like Canadian passports.