Double Strike Error Coins

In the days when coins were struck by hand, double-strike errors could happen fairly easily. A coin-maker, not certain that he had struck a good impression, or an apprentice learning the trade would find it hard to resist striking a second time. Usually the resulting image had extra impression-lines or might contain blurred printed letters in its legend.

Especially in imperial Roman times, demands for coinage were sufficiently intense as to foster several classes of double-strike errors. The need to provide regular pay to increasingly far-flung armies meant rapid recirculation of coins collected in taxes. One quick way to produce a steady flow of coinage was to over-strike worn coins or those remaining from a previous imperial regime (occasionally, a new emperor was commemorated on the face of a coin, while the back retained symbols or even the name of his predecessor).

Modern coinage machines still display occasional double-strike errors. Collectors watch especially for double-strike errors in pennies (perhaps their low monetary value means less rigid inspection of results).

While the classic gambler's two-headed flipping coin is a true forgery, double-strikes can be detected in authentic, circulating coinage to this day.