I recently bought a collection with many Whitman albums, and one of them was a 1964-date folder filled with 40% halves, proofs, and clad. There was also (what I assumed) was a 90% Kennedy half in a plastic flip on the last page. I took it out today and I saw its double headed! The coin weighs 12.00 grams and when you drop it on a counter, it has a dead low tone sound. I assume there is a Mexican 20 centavos coin inside. I've seen people get these in CRH but this is my first magic coin. Post your double heads, double tails, or any relevant coins!
We've got quite a few of these from searching. I'm not going to post them because they're in the trunk and that's one heavy load of boxes of coins in there. But there's one with a Mexican Centavo inside, that's right, though I forget the denomination. I don't recall any are silver, like yours, just clad, so yours is kind of neat.
The double headed coin does not have the 20 centavos inside. It’s own trick is it’s doubleheadedness. I only found 2 while roll hunting (1 1964 just like OP posted) while I found ~30 of the hollow coins containing a 20 centavos or whatever. Neat find.
Years ago I bought a complete set of double sided coins. One each, heads, and one each tails. 1¢ through 25¢. Lost a couple along the way and may have actually spent them by accident.
This evokes a still vivid memory: Years ago I was digging through a local coin shop and a shocked looking man came in and asked me "do you collect coins?" I said "yes" and he showed me, with awe pouring off of him, a two sided Kennedy almost exactly like the one above. All I could do was raise my eyebrows and keep looking through the inventory. When the dealer freed up, the man went to him and said "Look at this! I had a guy at another place look at it under a scope and he couldn't find a seam or anything!" The dealer took the coin and in 1 second pointed to it and said "it's right there. These are well known magic coins and, given how the minting process works, it's impossible for these to happen at the mint." The disappointed man skulked out of the shop and the dealer and I made quick eye contact in an "oh boy" type manner. I hoped that the poor guy didn't pay a ton of money for it. I never saw him again, though I spent a lot of time in that same shop.