Except it only overlaps on the Kos document. Someone fixed it on the Obama site version. Compare the lower corners of the border intersection for this:
http://www.dailykos.com/storyonly/2008/6/12/11012/6168/320/534616
and
http://my.barackobama.com/page/invite/birthcert
I pointed this out last week, but was summarily ignored. Save both to your PC then zoom in the lower corners. they are separately produced documents. Surprised?
So maybe it’s the degree of overlap, because on the real DeCosta doc, they do overlap slightly.