Transiting back through Shanghai

I'm flying from the UK to Shanghai and staying for 6 days on the 144hr free transit. I'm then flying to HK for a few days before returning to the UK. Which should all be fine according to the above info (i.e. A and C destinations are different).

The issue is that I've bought UK-Shanghai return flights and then Shanghai-HK return flights separately, so I will need to transit back through Shanghai again on my way back to the UK (but not leave the airport so shouldn't need another visa). Is that acceptable?

Thanks for your help!