Here are the pictures of the double stamped dime I found. It was the front and reverse of both a penny and a dime. It has ridged edges and is made on the metal of the dime.
It appears to be a "struck over a different denomination or series" error. This would have occured when a dime, (rather than a cent planchet) was fed into the striking chamber, and was struck by the cent's dies. If genuine, you have a very nice error coin. Coins like this are sometimes called an "eleven cent piece".
It is a little too hard for me to tell looking at the photos. So I will reserve comment. I would suggest that you send it to NGC or PCGS for certification. If it is indeed a duel denomination, you have a great find.
The pics are fuzzy, and the coin appears to be different colors in the two pics. But if it's a genuine 11 cent piece as Jody described above, it's a nice find indeed...but you won't get rich. I had 2 of these same coins last year...seems like one comes around every 4 or 5 months or so. One sold for $300, the other for $600. The difference? The more expensive one was very well defined on both strikes, both dates and most details were clearly visible from both strikes. The $300 coin was not as well struck/defined...it just wasn't as dramatic looking. Hope this info helps. Like ND said, have this certified. Good luck!
