Do I need double-entry tourist visa to return to China from HK?

I'm planning to apply for a single-entry tourist L type for PRC, but I also wish to visit Hong Kong for a week. Upon leaving HK to re-enter mainland PRC, is it technically a second entry into the country? Should I apply for double-entry type in this case? I'd rather not, because the single entry is cheaper and I'm on a very low budget.