It seems like on double page landscape view the last 2 pages are not joined and showed single page. Is there a way to disable this and have them show double page view?
It depends. The first and last page are always presented as single, this is because the reader mimics a scan from a book/comic. However, some scans do not have an even number of pages, or have some of the pages scanned together in landscape (it really depend on each file). So in some cases where panels can’t make pairs, the page previous to the last will also be shown as single page.