Hello @nerva44,
In cases like yours, it's generally recommended to use the hreflang tag. That will help you notify Google that pages with identiacal content are just different language versions of one and the same page.
Alternatively, (if you have your content on different sub-domains, e.g. site.com, site.co.uk) you may use a cross-domain canonical tag. Multi-language pages with identical content located on different domains should be pointed to the main one with this type of canonical tag.
You can learn more about the tricks of multi-language and multi-regional SEO in our blog post.
By the way, our extension SEO Suite Ultmate supports both a cross-domain canonical and hreflanf tags.
You may explore the demo version of the extension here: http://www.mageworx.com/seo-suite-ultimate-magento-extension.html
Hope it will help you to optimize your multi-language websites.
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