I am a malaysian citizen. Can I apply a two entry visa on my own? How long is the processing time?

It is possible for you to apply a double-entry visa on your own, it takes 4 working days for processing. However, the number of entry, stay duration, validity of China visa is up to the decision of visa officer. Nobody can assure that you will get it. The visa officer will consider your demand, if you really need to enter China twice, maybe the visa officer will issue a double entry visa to you.