You specify the main URL since the online search engine could have issues deciding which just one really should be the principal URL.  The following tutorial will demonstrate the best way to empower Canonical URLs in Prestashop 1.five. Yandex: Russia’s most widely used search engine also supports hreflang tags. https://www.presta-addons-modules.com/en/opencart-seo-automatic-google-rich-snippets-json-ld-integration-opengraph-twitter-tags-schemaorg.html