Can first time visitors to China apply for a double entry L visa?

I'm hoping to plan a trip from London to Singapore and back by train and am doing some research into my Visa requirements.

If it is my first time visiting China, as a British citizen would I be eligible to immediately put in an application for a double entry L visa? And are there any constraints on the overall time periods in which it can be used (for example, can I specify that I am applying for double entry over a 6 or 12 month period)?