The previous order on Ctrip was for two flights from two airlines (combined flights), and I would like to know if one invoice is issued or two?

According to Ctrip’s order rules, if the previous order is two flights (connecting) between two airlines, one invoice will usually be issued. If it is a flight with the same airline, it is also the same invoice. However, the specific issuance method may vary according to the specific operating procedures and regulations of the airline.