You specify the main URL because the online search engine might have difficulty identifying which a person really should be the principal URL.  The next tutorial will show you how to permit Canonical URLs in Prestashop 1.5. Ensure that your XML sitemap only consists of canonical pages. This will https://addons.prestashop.com/de/seo-suchmaschinenranking-optimization/31857-automatische-google-rich-snippets-json-ld-opengraph-seo.html