You specify the principal URL as the search engine could possibly have problems identifying which one must be the main URL.  The following tutorial will tell you about how you can allow Canonical URLs in Prestashop 1.5. Redirect into the canonical URL. A offered PrestaShop web site can have https://addons.prestashop.com/nl/seo-zoekmachineoptimalisatie-vermelding/31857-automatische-google-rich-snippets-json-ld-opengraph-seo.html