I'm having a layover in Guangzhou in a couple of weeks (a very long layover) and I was looking forward to visiting Hong Kong for the day as I know a few people there. However, I think this means I cannot use the visa free transit period since I am leaving the Chinese mainland and re-entering. However, I have two passports, an Australian one and an Italian one. I was wondering if I could land in Guangzhou, use my Australian passport for the visa free period, enter Hong Kong, then re-enter China with my Italian passport, and use the 24 hour transit time for Guangzhou from Hong kong with the Italian passport? Let me know if this makes sense. Thanks!