Yesterday I posted an image of a contemporary Hawaiian COLB (July 1961) as a copy made in 1965. The image was a "photostat" which oldsters will recognize as it appears as a photographic negative. (prior to widespread use of copy machines, copies of "official" documents were made using a large view camera with a finite conjugate ratio copy lens to take a 1:1 magnification of the document on photographic paper). The image I posted followed the same format of the Obama copy with the exception that it did indeed show an embossed seal intersecting both signature and date of copy. It appeared to be a separate document which was placed in the frame of the COLB image to signify the overall image as a "True Copy".
Obama's COLB appears to have been copied (scanned) from a bound book (curved lines on the left margin) into a "PDF" format of more then a few layers with differing elements of the document appearing on different layers. The section at the bottom appears to be typed directly on to the safety paper and the signature was applied with a stamp. There is no seal of any type applied as on the older documents from 1965.
Regards,
GtG