we fly to Beijing and then to Seoul and then back through Beijing to travel home to Canada.

we fly to Beijing and then to Seoul and then back through Beijing to travel home to Canada. I am only concerned on the Chinese policy as we do not require a Visa for South Korea. I just need to know if we can get the 72-hour free transit exemption twice in two weeks at each end of our travels.
We will be in Beijing for approximately 48 hours prior to travel to South Korea and then about 55 hours between South Korea and our trip back home to Canada
and would like to pre-book some tours for those times if possible
Is this possible??