You specify the primary URL since the search engine can have problem identifying which one really should be the main URL.  The next tutorial will tell you about the way to help Canonical URLs in Prestashop one.5. Improve the indexing of your Prestashop urls in Google. This module AUTOMATICALLY https://bookmarksden.com/story19361565/about-automatic-hreflang-tags-canonical-tags-all-pages-seo