I am issued a M type visa single entry can I make in double entry. Also can I extend my stay 60days

Mitra, I’m afraid you cannot make in double-entry unless you re-apply for a business M type. But you are just given a single-entry M type this time, I don’t think you will be given a double-entry one when you re-apply.
It’s possible for you to apply for an extension after you enter PRC.