A material legal distinction may exist between a marriage that has been consummated and one that has not. If the first effective divorce changes the marital status on which a subsequent expression would operate, later words may have a different consequence.
Thus “أنت طالق ثم طالق” is more than an exercise in grammar. Ask when the first pronouncement became effective, what legal relationship remained when the next words were used, and where the delay signaled by thumma applies.
Differences of legal opinion arise from precisely these underlying distinctions, not from merely counting repeated words.