A repunched mint mark occurs in the same way as repunched dates; the punch was struck more than once when the device was added to the die. John Wexler’s article on repunched mint marks says it all, and has a fantastic photo! Click here.
We have only one repunched mint mark in the Indian Head Series, the 1908 S RPM-001. The San Francisco Mint did not begin coining cents until 1908, which are distinguished by an ‘S’ mint mark on the reverse under the wreath. Be wary of all Indian Head Cents with a mint mark, as they are targets for the mischievous. Several different counterfeits have been found for both 1908-S and 1909-S Indian Cents.