You specify the key URL since the search engine could possibly have trouble determining which just one need to be the principal URL.  The subsequent tutorial will explain to you ways to allow Canonical URLs in Prestashop 1.five. Canonical URLs are applied to prevent replicate written content and to https://addons.prestashop.com/en/seo-natural-search-engine-optimization/31857-automatic-google-rich-snippets-json-ld-open-graph-seo.html