http://s255.photobucket.com/user/pitw75/media/Gold items/IMG_0547_zps753901ac.jpg.html Pic of the mark through 20x inverted lense: http://s255.photobucket.com/user/pitw75/media/Gold items/IMG_0554_zps5e6debff.jpg.html
Interesting, it was purchased from a well respected dealer, what makes you question its authenticity?
I agree with Matt, the coin looks like a cast fake to me. No idea what the extra mark is from or what it might mean. And for whatever it's worth, that mark was there when the coin was made.
The mintmark looks mushy to me. The letters dont look as sharp as they should. I agree with others questioning the authenticity. If its a respected dealer, he should take a refund on a coin that is proven to be suspicious. I would take it to another dealer and see what is said about the coin.
OP, when you post an image directly from Photobucket, some personal data, including your name (and your one public album) shows up along with the image. Surely you don't want that??
My guess as to the stamp would be a counterstamp. Not sure of its origin, though. I, too, am skeptical of the authenticity of this coin. The texture of the fields, most noticeably below the mint mark seems typical of a cast fake. There also appears to be a raised rim on the coin most visible in the picture between 12 and 3 o'clock. This should not be present on a real coin. Additionally, the details look inconsistent - the olive branch is mushy and less detailed than would be expected given the state of the eagle's feathers.
Click on the OPS's link, then use the + sign to blow the picture up to full size - it'll fill your screen. Then look at the D and the mark. The D, and the mark, were made at the same time. That is no counterstamp. The corner of the mark is actually under the D.
I was thinking about this piece today... I have never seen another like it... Maybe it's a lesser known middle eastern counterfeit and it might bear some sort of hallmark unique to these... Worth a further look.
When I blow up the other photo using the same technique, it looks pretty close, but I'm not convinced it falls under the D. But I agree with you and others...something seems off with this coin.
Looking at this - http://i255.photobucket.com/albums/hh145/pitw75/Gold items/IMG_0547_zps753901ac.jpg~original - you can't tell that the upper right corner of the square is covered by the bottom corner of the D ?
I'm not convinced that the upper right corner of the square is under the point on the D. It almost looks to me that the lower point of the D was displaced outwardly by whatever made this mark. That said, looking at the various details of this coin...things don't look right. Some of the details look "mushy" so I'm in agreement that the authenticity is questionable. Without seeing the coin in hand, it's hard to know for sure (on either point). But, it looks suspicious.