Google is valuing canonical URLs within a website’s sitemap files, and Gary Illyes took to LinkedIn to tell users that they should “include the URLs that you would want to see as canonical in your sitemaps.”
While Google has advised to do this on many occasions, Illyes explained in more detail in an effort to implore more people to do so.
“It’s normal to have some duplicate content on your site, but you want to give search engines as many hints as you can about which version should be canonical (I.e. shown in search results)” he said, in the LinkedIn post. “Sitemaps is one of those hints. Not as strong as rel-canonical and definitely not even near redirects, but it can be useful still.”