How do you travel to Canada and return to China holding both a PRC?
If you were a very naughty person youd go into Hong Kong on your Canadian passport and on into China on your Chinese passport. And remember to use the right ones when you go back out. Hong Kong and Canada have a visa free thing and so does China and Hong Kong so theres your free way in. Hypothetically. Because if you have a Canadian passport youre not allowed a Chinese one any more. Its very naughty.