I am Flying to Shanghai and Hong Kong from New Delhi. Do I need single entry or double entry Visa?

Ranji, as for your first stopover in Shanghai, you don’t need an entry permit because you are eligible for the 24 hour direct transit. If your second stopover in Shanghai when you return is less than 24 hours, you don’t need it either.
But if your layover time in Shanghai is more than 245 hours for your second transit, you should apply for a single entry permit in advance.