It doesn't indicate an inexperienced trainee pilot, only that he/she was new to this particular aircraft.
It could have been an annual line check. Both PF and PNF might well have been well-experienced on type. It doesn't necessarily mean either was new to the aircraft. Presumably this would also be classed as a 'training flight'.
One captain and two copilots. I put my money on this being a training flight with a new F/O.