I have heard about those plates but never saw one. The DJ3A used a sticker, again, I have only seen pictures. You might want to see if Joe Friday on the 2A page knows anything about it, he's pretty knowledgeable about that stuff.
As far as the chances of you jeep being the same trim and paint as the next....Its a crap shoot. i wouldn't bet anything of value on it.
I haven't looked in our database for it yet, do we have ANY consecutive numbers listed?
This plate is on your Dj6 ?