We will be on a cruise in March and have a stop in China

on 2 different occassions for 1 day both times approximately 10 days apart.
We know that we can join a cruise tour and they will organise it all for us, but if we want to step off the ship and do our own thing for those 2 days, do we need the single entry visa, valid for three months, or the double? It's very confusing.
Thank You, Rose from Australia