When you search for flights with Duffel by creating an offer request, we'll send your search to the sources you have enabled, collect up the results and then return them back to you.
We call our search results "offers". Each offer allows you to book a particular set of flights (known as "segments") for a particular price.
You might get multiple offers that contain exactly the same set of flights. This can happen for a few reasons:
- An airline might offer different "fare brands" with different features or benefits - for example, British Airways offers a hand-baggage only brand called "Basic" and a premium option with checked bags called "Plus".
- Multiple airlines might be selling the same flights under special agreements known as "codeshares" or "interlining". For example, Lufthansa sells flights operated by Air Canada.
If you want to match together offers that are for the same set of flights, you can do this by looking at the `operating_carrier` and `operating_carrier_flight_number` of the segments.