Central field was ground down in order to receive the plaque's new engraving while some of the original engraving can still be seen on both sides of the new recessed rectangle.

I've even had (sloppy) examples where an "F" could still be seen on the reverse of plaques that went to Uruguay for resurfacing and a "P" that were resurfaced in Cuba. With one sloppy job; the previous serial conrol number was above the new engraving, upside down. How do we know they were resurfaced at their new destination? Easy. They were found in various stages of being reworked... and, if you think that's interesting; the next time you're running around fleas in Europe, take a look on the back of some of those MOP buttons. You just might find some of the rarest chips known; totally mutilated...