I have dual citizenship, US and Italian. I already have a 3 month business visa on my Italian passport and already have the extension for other 3 months. Given that the visa is going to expire soon I will have to leave china to apply to another visa.
However, can I apply for another 3months business visa but in this case with my US passport? And, when I enter china, should I show both passports one with the old and the other with the new? Or just the new one?

Thanks in advance.