Hi, I like to hear your opinions about this coin and the exact value of that, if it is possible, please!
I never heard of a double die.. But there is such a thing as a Doubled Die. Which yours is not. Doubled die is a term in numismatics used to refer to a duplication of design elements on a working die created due to a misalignment of the die or hub during the hubbing process.
In mint mark D clearly shows the doubling. Did you notice in a large magnified picture? By the way thanks for the corrections.
Pre 1990 Mint Marks are never Doubled Die. They cannot be. Why? Because they were hand punched onto the Die. It can be a RPM though.. That would be a Repunched Mint Mark D/D or D over D
See this page regarding 1960 D mint marks. http://www.varietyvista.com/02b LC RPMs Vol 2/RPMs 1960D (1-60).htm