I'm certainly no expert on Bust and Harp Tokens but I will tell what little I know and perhaps one of our Token experts can add to it.
Yours appears to me as a genuine token. There were many imitations of these produced. They were originally produced in 1835 with that date on them. Then they antedated the dies to read 1820, first by overprinting the 1835 date and then producing a non-overdated die for the final production. Yours sure looks like to be the overdated version. If it is, it could be fairly valuable.
Do you mind me asking what you paid for it?
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