What if I have a residence permit in Hangzhou and a residence permit in Shanghai?

It didn't work. Because of work needs, a person can apply for residence permit in more than two places (cities). Therefore, the residence permit in Hangzhou has no effect on the residence permit in Shanghai. As long as the application criteria and conditions are met, local citizens can enjoy the same treatment after the application is passed. Residence permit is an attempt made by some developed cities in China to learn from the "green card" system of developed countries, which has accumulated experience for China to formulate skilled migration measures and eventually form the national "green card" system of China.