A spectacular error, maudry. It looks almost as struck, so I guess it fired the interest of a contemporary of the French revolution, who kept it to show, rather than spend it. I am reminded of the aftermath of the storming of the Bastille. The medieval castle was thoroughly and completely taken apart by ... souvenir hunters!
It says something quite positive about the human spirit when blind rage, killing and deep frustration with injustice can so quickly be replaced by elation with "teaching the bastards a lesson" and wanting a souvenir of the accomplishment.
Peter