Yes, that makes sense to me. Perhaps I can do a better job of explaining my issue now that I've been thinking about it for a while longer.
This is quite perplexing. I very often render hemispherical XRs and I want 24 images in the rotation at 4 vertical increments.
For whatever reason, the initial view of each vertical increment is duplicated at the end of that rotation, so image 0_0 & 0_24 are the exact same position of my object. The same is true of 1_0 & 1_24, 2_0 & 2_24, and 3_0 & 3_24. This is why I have to put in 25 horizontal increments; if I don't I essentially get 23 increments after the duplicate image is removed. If I were to put in 24 for the horizontal increments, I would not get straight on images for the front, right, back and left sides of my object. It almost seems to be treating 0_24 as if it was supposed to be the last increment of the rotation.
I hope my explanation makes sense!