You specify the principal URL because the online search engine might have issue deciding which one particular should be the principal URL.  The following tutorial will tell you about the best way to permit Canonical URLs in Prestashop one.5. Adding this code to each page of your web site https://addons.prestashop.com/es/seo-posicionamiento-buscadores/31857-google-rich-snippets-automatico-json-ld-opengraph-seo.html