For the "pagenum" pagination algorithm, the following URL has false positive for "next page" link.

http://altwall.net/texts.php?show=bullet&number=2642

The detected next-page link is actually pagination for the comment only. This results in repeated content in the stitched view.

One easy workaround is to skip appending the content if it's exactly the same with the first page, but this probably won't be robust enough.