i guess I have asked this question in one form or another, from time to time. physically how does a doubled die coin actually occur. I have been searching (unsuccessfully - so far) Lincoln cents. I have found several types of errors. lamination, die breaks,
Struck Through Grease, misaligned die (only slightly misaligned), one
Cud (a nickel). so far ZERO confirmed DD, (although I have several in my "check closer" stack. so I really don't know what physically happens - in the process, that causes the elusive "doubled die". thanks