Coins that exhibit machine-doubling are interesting, not to mention being pretty cool. They aren't really considered errors, though. Sorry, no big value on this one.
This isn't a doubled die, but rather a form of mechanical doubling or 'machine doubling' as Jody states. No big premium on this, but they are commonly bought & sold on Ebay. Most numismatists consider maching doubling to be nothing more than damage. Machine doubling on U.S. coins is quite common,even on modern coins. ~ Jim
