AirlineFlightSchedules result problem when including airline

I am using the AirlineFlightSchedules api call to get a list of flights. However, on certain cases, when I include the airline parameter, the results include other airlines too.

For instance, when I set airline as AFR (Air France) and airport as CDG (charles de gaulles), I get results including Air France and Air Europe, Aeroflot Russian Airlines, and many other airlines.

Those are codeshare flights that are known to operate for your selected airline and match the other criteria.