You specify the primary URL as the online search engine can have difficulty determining which one really should be the main URL.  The next tutorial will show you how to permit Canonical URLs in Prestashop 1.5. The default homepage title could be the title of the store, and thus https://addons.prestashop.com/fr/seo-referencement-naturel/31857-seo-automatique-google-rich-snippets-json-ld-open-graph.html