These come from the NSA originally - so it's probably SOP to make slight changes to every page of every document each time it is released to someone, so that they can track the exact source and path of any leaks.
I don't doubt they version things like this, but I do doubt the watermark is easily found. A bit here, a bit there and you can bury a lot of info in a graphic with no one the wiser.
On the US-map one, the ellipses line up correctly with the cable landings, and the PRISM-partner logos are over the US, not floating in the ocean. Also, the arrowheads on the cable-bundle ellipses aren't all distorted, and the drop shadow on the "You Should Use Both" text displays correctly.
I'm marking this one down to PowerPoint-specific rendering (vs, say, OpenOffice).
