I don't know the seasons well enough to know which picture came from which season. So this is just a theory.
But is it possible the 'equal' billing picture/name came from the season where they were "and the rest", and the 'uneven' billing came from when they were "the Professor and Mary Ann"...
Well, it was made entirely on film - no video involved in its production. And I’ve never heard anything about the negatives being lost or destroyed. So I would think it’s possible.
Now whether the owners want to release it on Blu is an entirely different question.