You specify the first URL because the search engine could have difficulty deciding which 1 really should be the key URL.  The subsequent tutorial will provide you with ways to allow Canonical URLs in Prestashop 1.5. Increase the indexing within your Prestashop urls in Google. This module AUTOMATICALLY provides, https://addons.prestashop.com/es/seo-posicionamiento-buscadores/31857-google-rich-snippets-automatico-json-ld-opengraph-seo.html