The differences? Well,
Machine Doubling shows shelflike reduced in size doubling. The machine caused the doubling, hence the term
Machine Doubling. An actual Doubled Die is actually increased in size, and not shelflike in appearance. A Doubled Die shows doubling on the die. Happened in the die making process. Visit doubleddie.com, for more information. Please read the information.
http://doubleddie.com/58222.html
Errers and Varietys.