If I have a valid Chinese visa in my passport and am eligible for the 240-hour visa-free transit, but I would like to save the visa for my next trip to China, will the border inspection station use my Chinese visa for entry this time?
english.shanghai.gov.cn
A: No. For passengers who are eligible for the 240-hour visa-free transit and hold a valid Chinese visa, the border inspection station will give priority to the 240-hour visa-free transit. However, if you require to stay in China for more than 240 hours, the border inspection station will handle the formalities with your Chinese visa according to your request.
Source: Shanghai Exit-Entry Border Inspection General Station