Pages now have a desktop & a mobile version -these have an “m.” prefix, desktop pages have no prefix. Pages will re-direct to the page for your device, but for subjects within a page use the index for your device. Both Sitemaps show all pages, so all subjects have two entries, desktop & mobile and share the same number. I hope my reader enjoys the convenience, Google preferred. If you click the wrong one, it should redirect to the correct one for your device in a few seconds.