Hi Stu.
Yes. There's your answer. LOL
If there is a divider between the two horns, then one could speculate that it would be used to carry a larger quantity of powder in one horn without the clumsey banging around of two medium sized horns or one of those extra large horns. Once the one horn was empty, you would just turn it around on your shoulder and start with another full horn. LOL Just a guess.
But, if the horn is hollow through, I don't know.
Rick