Sorry but it's machine doubling, which is common and adds no value. The doubled devices are flat and shelf-like, not full and rounded from an offset impression from the working hub. Also Notice that the mm is doubled. This wouldn't happen on a true doubled die because the doubling occurs when the die is pressed into the hub. Prior to 1989, the mm was added to each die by hand after it was finished with with the hubbing step, so you would not see a doubled die AND mm. Hope this helps
Although, sometimes due to chance it did occur together as they are independent operations, even though very very seldom. Example is the 1960-D DDO( small date/large date ) D/D rpm. http://www.lincolncentresource.com/doubledies/1960Dddo1.html Jim
