Is it possible for a single flight to have multiple flight numbers?
Yes the same flight can have multiple flight codes if it is run in codeshare agreement between multiple airlines. Quoting from the linked page:
Typically, a flight is operated by one airline (technically called an "administrating carrier"1) while seats are sold for the flight by all cooperating airlines using their own designator and flight number.
Hence why the flight can have as many codes as there are airlines selling seats on it.
In your example, the flight is operated by Air France in codeshare with Flybe, Alitalia, and many more.