Same Flight?

I tried to see what flights are available to go to Calgary. There seems to be 2 choices. One is to transfer at Vancouver, the other at San Francisco. Since I may want to stop at San Francisco to visit few friends, booking a round-trip flight to San Francisco directly, and another separate round-trip flight from San Francisco to Calgary might be an option, since I won't be in a hurry.

Cathay Pacific still offers very competitive price. Round-trip to San Francisco cost 23155 NTD, including taxes, which is around 660 USD. But wait, for the same flight CX872, same date, same cabin, on the second row, there are 4 seats left, but on the fourth row, there are 5 seats left. Are they really the same flight, or am I dreaming?

Well, there are several flights from San Francisco to Calgary every day, and the price is not bad. Both United Airlines and Canada Air offer at 277 USD. Although United Airlines offer passenger to stop at transfer city, but there is a fee for it. Pros and cons. Pros for 2 round-trip tickets are cheaper price and flexible itinerary. Cons are logistics for lodging and that I am not sure what to do if flights are delay and thus I miss the flight. Well, I’ll think about it.