You specify the main URL since the online search engine might have problem identifying which a person needs to be the key URL.  The following tutorial will teach you how to permit Canonical URLs in Prestashop 1.5. Improve the indexing within your Prestashop urls in Google. This module AUTOMATICALLY https://addons.prestashop.com/fr/seo-referencement-naturel/31857-seo-automatique-google-rich-snippets-json-ld-open-graph.html