US Citizen teaching in China VISA help.

I will be traveling in August, but in October I need to travel to Kowloon, Hong Kong Exam Authority to take an American standardized test only offered there. I will be entering with a Tourist L, and then traveling to Hong Kong sometime within 30 days (by mid September) of entry to obtain a work (professional) Z until July 2014. Since I need to return to Hong Kong again in October for a few days, I will need a Dual Entry Work Z (during my September trip) to re enter(PRC) upon my second return trip from Kowloon in October, correct?