I agree, from what I can tell using the given pictures, it doesn't appear to be verdigris. A better solvent that acetone for removing this would have been xylene. I've found acetone really isn't a very good solvent for copper. Acetone is OK for removing light surface debris (like dust) and fresh fingerprints/oils, but that's about it. Xylene tends to solubilize the long-chain organic compounds typically found on copper coins.
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