stoping in Shanghai twice during the same trip

Hello,
I am travelling from Vancouver with a Canadian passport that way:
Vancouver-Shanghai (stay in Shanghai 1 day)
Shanghai- Hanoi (stay in Vietnam 10 days)
Ho chi mint - Shanghai (stay in Shanghai 3 days)
Shanghai- Vancouver
Can I enjoy the 144-hours visa when I arrive in Shanghai from Vancouver and again when I arrive in Shanghai from Ho chi mint
Thank you for your answer.