Entries in China (Beijing)

Hi all!
I am coming to Beijing for 2 months and I have a 2 entries visa, each entry is 30 days.

I have a roundrip flight from SFO-PEK. In the middle of the trip, I will go to Tokyo for 2 days and come back to Beijing. That's my second entry in China.

Before I leave, I'd also want to go to Thailand, and then fly back to Beijing (I don't need to leave the airport) and take my PEK-SFO flight back. Would that be my 3rd entry? Will I have any problems, even if I stay at the airport only?

Thanks!