So much fun going through 1.5kg of cents. Found one (1946D, 7 in the lot) where the mint mark is touching the number. Being new in numismatics brings me to the following question. Are the mint marks put on with a separate die ? Hope to hear from you.
Yes. I don't know when mint marks were made a part of the finished die, but before the change, mint marks were hand punched into the finished die.
"Machine Doubling," or sometimes it's called "Mechanical Doubling." They're both synonymous with "Strike Doubling."