I also have recently acquired a 1956 D wheat penny struck on a nickle die. I would have the weight for you, but my scales just took a dump on me.
I realize this is an archaeological thread. How did the nickel fit in the penny coining machine to be double denomination struck? It is not as if it was a cent planchet which was struck, and then struck again in the nickel press. Here is the photo: (something is not right about this)
Yes but the photo shows it is the size of a nickel. With full nickel rims. And the nickel is not on top of the penny, the penny is on top of the nickel. I suppose it could be "wrong stock" if it is copper, but the nickel size can't fit into the cent coining press to be struck the 2nd time. Maybe check Mike Byers he always seems to buy these whether they are real, or created. Perhaps he has a photo of such a coin in a slab.