Earlier this year, I almost missed an international flight. I noticed that I was running late while I was still at work, and considered going from work straight to the airport. But I realized that my passport was at home, so had to go home, and then to the airport, which cost me lots of time. Boarding had already started when I finally reached the gate.
At work, I had my EU state ID on me, which would have been considered a valid travel document for this flight as well as in my destination country of Spain, but I had entered my passport number when booking the ticket, and was afraid I wouldn't be allowed to board with the other document.
To prevent such problems in the future, is it possible to buy plane tickets and give two alternative document numbers, for two different IDs of the same person? If yes, what does it depend on? (Airline, fare, etc.)