Recently I was working on a website for a customer. They were trying to improve their SEO. The last webmasters they had, did not bother to create a google webmaster tools account. With permission from the client, we created a webmaster tools account. We had to wait a couple of days until we had access to the data.

Finally the data came in. We analyzed any errors the website may have. The first section to look for is the Duplicate title tags in HTML Improvements under Search Appearance. These were the results:
Addressing the following may help your site's user experience and performance.

Meta description Pages
Duplicate meta descriptions 276
Long meta descriptions 0
Short meta descriptions 1


Title tag Pages
Missing title tags 0
Duplicate title tags 288
Long title tags 0
Short title tags 0
Non-informative title tags 0

Non-indexable content Pages
We didn't detect any issues with non-indexable content on your site


as you can see, we have 288 pages with duplicate titles. After looking through the data, we see that most of the pages contain the url http:www.example.com/page1.html?video_link=http:www.example.com/page2.html

We investigated this issue and found the that Facebook is creating all these errors. We are continuing to research how to avoid and get rid of these urls, We checked the HTML code and found nothing.

We will update you on any findings.

UPDATE: we also found ?fb_xd_fragment and ?fb_locale=pt_BR