>> This site says: "Since any seed produced is generally sterile, French tarragon should be propagated by cuttings or division."
It sounds like French tarragon doesn't come from F1 seeds (from two other lines), but instead never comes from seed. Finally Googling, I come to the same conclusion you did.
I do think that some vendors think "the right ID is whatever sells best". I have noticed "seed catalog name drift", usually only in common or informal names, to be whatever is deemed more popular that year.
For example, "mustard" is unpopular, but "wasabi-like" is popular.
One nursery advertised Lavatera thuringiaca 'Barnsley', a fancy "periclinal chimaera". But they sent plain old common Lavatera thuringiaca 'Rosea'. True, all 6 might have reverted while in the mail!
