Posted 01/28/2014 2:59 pm
It isn't that uncommon of an error, though it may be tough to find on this type/denomination. A clamshell split may result from impurities in the metal (it often isn't present or noticeable until after the strike and some circulation). The top layer of this one has broken apart - I would consider it damage. Sometimes these errors are "helped" by those who try to pry the layers farther apart.
