Immediate answers for when you think you have a
DDO,
DDR, or RPM.
Check out varietyvista.com. See if you can find an exact match to your coin.
If not, then you almost certainly have a non-collectable type of doubling such as
Die Deterioration Doubling or
Machine Doubling. You would then go to error-ref.com and look up "doubling" to see all the types that can happen and you can tell what your coin is.