For some reason certain pages add the "fb_xd_fragment" parameter to pages. This is caused by the facebook like button bug, apparently the solution is to rollback to the previous facebook SDK.
Since my site is set up in htaccess not to disallow any parameters with "?", this is what happens: 1) normal page: http://www.example.com/mypage.html display correctly 2) page that got additional parameter [mysite.com...] shows blank (but with 200) I've run this in Google: "mysite.com"+"fb_xd_fragment" and it results in 0.
I guess I managed to avoid a catastrophe and have the majority of my pages duplicated.
I rolled back to old facebook SDK (using iFrame). My question - should I keep everything as it is now, or should I take further steps? Like create redirects from fb_xd_fragment to normal pages? I was tempted to do this, but then remembered that it is not smart to fix something that hasn't been broken :P
I have just put it on my one of my sites, started getting a few likes, I did however tell WMT to ignore the parameter. I dont like the sound of it creating blank pages, I wonder what effect it will have on the site in the serps. hopefully none.