Hi, you post got me really excited, as I have a coin very similar to yours & have been searching for info for a VERY long time. My coin has a roman coin welded(?) to the inside. Its an 1856 Napoleon III 10 Centimes Coin with a Secret Compartment. I:ve found a second one (I was very excited & bought it straight away) & its cost me $250.00 aus to purchase & be sent to Australia. it has nothing in its centre. I will attach a photo of the one I have now, as the second one is being shipped lol Good luck