Google has been trying to improve the way it detects duplicate content on a website. URLs with parameters, such as the ones used for pagination, are tricky. You have the option to add a link tag to help Google identify this content. To read more about this check out the blog post in the Google webmaster blog.
To implement this in a Joomla template you can add the code in the overrides. For example you can open root/templates/your_template/html/com_content/blog.php. Inside it add this code:
The variable $pagdata contains all the information about the pagination for the current page. We simply make a check for a next or previous page link. If there is one it means the page with other items exists so we can add the link tag. We do this with the addHeadLink function.

@Damien
Yes it does, we're using it on this website. Of course you'll need to edit the K2 overrides instead of the default content ones.
does this work for k2 as well?
You're welcome. Thanks for finding the typo, it'll be corrected now.
Just Excellent work brother. Many many thanks. You are very helpful.
I just replaced this code ' if($pagdata->previous->link) ' and it worked fine.
Best Regards,
All Praise to Allah(God), & Blessing be upon to Prophet Muhammad(S).