Here's a listing that I believe slipped by many error collectors due to the novice listing mistakes of the seller, I can't wait till they show up to take a look at the blank back 1975 penny. Read the fine print. Item number: 370577214961 on good ol eyay.
Here's a new arrival which perhaps can be explained by someone more experienced. Brockage-Counterbrockage may be the term, or else maybe a brockage coin which followed a flip doublestruck brockage coin?