Let me preview an example of a not true doubled die error.
Die Deterioration Doubling (DDD)
That is what you see above. The die used to the make the coin is going bad and the edges of the design start to flow outward and spread. That causes a doubling and other problems. As the die starts to break down they are polished again and used for a while leaving classic straight polishing lines.
None of this adds value and in high grade coins will actually lower value.
|Tilted and repositioned you can see streaks or lines running across the entire coin, these are polish marks.|
|The back is also full of Deterioration Doubling and the zinc core is partially exposed.|
|Lincoln's hair has a slight doubling.|
|The P in PLURIBUS shows the most extreme doubling but every element on the reverse has the bad doubling.|
|The die deteriorating raises the metal on the design and when pressing the coin it forces more copper out of the way exposing the zinc underneath. the copper plating is very thin and if the design cut is too deep it will show the zinc core.|
|Again tilting the cent shows most of the doubling and artifacts like streaks and exposed zinc.|
|It is like a hill of metal or a drift or pile like after a snow storm.|
|Even the building has the problem as you can see the zinc coming out on the left hand side.|
Among all coins this is common but it is most often seen among the cents in the U.S and Canada. Nickels also sees this kind doubling often since it takes a greater force to make a nickel and the metal flow is great causing faster deterioration.
Let me emphasize these are errors but not valuable kinds. This is just worn and old dies and since it happens often that does not make it valuable. Sometimes called a "Poorman's Doubling" it fools many to think they have something rare.
Should you still collect DDD error coins? I would say no but some extreme examples looks cool and as long as there is eBay there is always a market.