You specify the main URL because the search engine may have difficulty pinpointing which one particular needs to be the primary URL.  The next tutorial will show you the way to help Canonical URLs in Prestashop 1.5. The default homepage title is the name of The shop, and as https://addons.prestashop.com/it/seo-indicizzazione-naturale/31857-google-rich-snippet-automatico-json-ld-open-graph-seo.html