haps
Highest subject score is DUX
Obviously in schools teachers are never going to be fully impartial and objective so there would be a bunch of reasons outside of actually who is better at vce french as to why someone else was awarded "dux". Subject score is actually objective.
You may have not got the award of "dux" but you duxxed the subject so it's fine imo
EDIT: probably would be more embarrassing to say DUX if you just got the teachers award and not the actual highest score