Make sure to look for coin varieties on them. DDO
and RPMs. Cuds could be hiding on the reverses of the coins as well. Any questions on what to look for, check out the sites like coppercoins, Variety Vista and doubleddie.com. Then you will know what to look for and stop looking when you don't see anything like what is on these sites. When you get look too hard, that is when you will think Machine Doubling
is something, when it is not. Feel free to ask questions. We all want to share with what you find.