I'm not familiar with all these plugins, but Best Facebook Like button, Easy add thumbnail, Facebook like box, Social Media Widget seem like good candidates.
Using one of them is fine, but as soon as you add another you create duplicate meta tags, and Facebook recently started rejecting Publicized posts that include 2 sets of Open Graph meta tags.
Could you try to deactivate them all, one at a time, until the error disappears in Facebook's debugger?
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.sportpeople.net%2Fsport-people-n2013-42%2F
http://i.wpne.ws/T2rq