The 'Double Eagle' situation is more complicated than that in most ways, but in other ways a lot simpler. It involves 1933 'Double Eagle' ($20) gold pieces. FDR banned private ownership of gold in 1933 and the various US mints were instructed not to mint gold coins. At the last moment, one of FDR's advisors convinced FDR to make ownership of ALREADY minted and ALREADY officially issued (i.e, 1932 and earlier) gold coins legal for collectors. Through some mistake the Philadelphia mint didn't get the order or act on the order in time and minted some 1933 $20 gold pieces, but they were never signed into circulation.
In fact, there's paperwork where the bag was double-checked by weighing and then melted back down.
Until the coins were signed into circulation and issued, they weren't currency and they constituted counterfeit coins. They were never legally issued.
The problem is that some mint employees were taking payments from coin collectors and coin dealers to pass along misprints and rare coins - all illegally.
Anyway, soon after all the '33 Double Eagles were supposedly all melted down, it became knowledge in the coin collecting world that a Philadelphia coin dealer had around twenty of them. The evidence suggests he got them from the mint official responsible for melting them down, who apparently substituted some earlier Double Eagles in the bag that was melted down.
At any rate, they were never issued by the government and they were counterfeit coins and illegal to own, as gold, and illegal to own, as counterfeit coins.
King Farouk of Egypt collected everything. His agents quickly bought a coin from the dealer. Knowing that ownership of gold in the U.S. was illegal, they sought export papers. The export officials were not experts in coins and didn't know there was a difference between a 1932 and a 1933. They gave Farouk's agents an export license.
Over the next twenty-plus years, a few collectors contacted the FBI to see if the 1933 Double Eagles they owned were legal. The FBI confiscated them and won court in which it was ruled that the coins were never issued by the government and were counterfeits and illegal to own. Other names are whispered in coin circles regarding owners of 1933 Double Eagles around the world.
However, when Farouk fled Egypt in the 1950s and left his collections, the auction catalog showed a '33 Double Eagle. The US government claimed a right to it. The Egyptian government pulled it from the auction and it disappeared.
Years later, a Texas oil man and coin collector was offered Farouk's Double Eagle through a London coin dealer. Word got out through coin circles. The FBI heard about it and seized the coin at the point of exchange of money.
There was a lawsuit. This time, the judge wanted the government to prove that the coin was stolen from the mint. The oil man and the government settled by putting the coin up for auction, with the oil man and the government to split the proceeds. The coin would be 'issued' by the government after the auction, making it more valuable to, and legal to own by, the collector. It was estimated to sell for a couple of million, but I believe it sold for $7 million to an anonymous buyer, who then put it on permanent loan to the Treasury Department.
Fast-forward about fifteen years, and a man suddenly 'discovers' ten mint 1933 Double Eagles, delicately wrapped. Turns out he's the grandson of the coin dealer through whom all of the other Double Eagles flowed - the ones that were seized by the government and recovered on the grounds that they weren't issued and Farouk's. The guy who had a reputation for paying off the mint employees to 'remove' rare stuff illegally from the mint for him, and the guy who, all evidence suggests, arranged to have '33 Double Eagles 'removed' from the mint for him. The key is this: they were never issued by the government. There are records showing that they were all supposed to have been melted and that a bag of gold coins of the precise weight was melted. If they exist today, it's because somebody at the mint took them without authority passed them outside the mint. Because they were never issued by the government, they are considered counterfeit coins. And they happen to be in the hands of, conveniently, the grandson of the guy who passed the original illegal '33 Double Eagles. This court wants the government to prove that they were stolen and it's difficult to do 80 years after the fact.
To me, it's like this: You build five custom motorcycles in your shop. For whatever reason (emotional attachment, change in law), you decide not to sell them. The next morning, you come down and four of them are gone. You file a report. One year later, you catch a guy riding one. He bought it from Bob Scoutmaster. You go to court, show you never sold them, and get it back. Five years later, you catch a woman riding one. You go to court, show you never sold them, and get it back. Twenty-five years later, this guy posts an ad on eBay selling two of your motorcycles in mint condition. Turns out he's the grandson of Bob Scoutmaster. You go to court. Now, despite all of your 25-year-old paperwork showing you never sold the motorcycles, and that you've been slowly finding the stolen ones and getting them back, this one judge says: "prove that your motorcycles were stolen. I don't care about your notarized 25-year-old statement that you're not going to sell any of them. I don't care that you've been running ads for 25 years trying to recover them. I don't care that you never signed any titles to them. I don't care that you've taken this position in court before. Find somebody who saw a person steal your motorcycles."