That isn't actually a bug. That label next to the page order is indicating the total number of pages that will be used for that file in the song. If you enter 1-3,1-3, then the total pages used for that file is 6. I will have to think of a better way to distinguish that from the raw number of pages in the file (which is shown at the top of the page order dialog for reference). So I'll either get rid of it that label entirely, or change it to read more like, "Number of pages: ", or "Total pages in page order: ". If you add like 5 different PDFs to the song, I just wanted there to be a quick way for the user to tell how many pages are present for each file in the song.
Mike
Mike