These were issued in sets along with the 3 cent J618-J620/P687-P689 and 5 cent J633-J634/P704-P706. To view the set, click here.
Pollock described both a high date and centered date for these at least in nickel J608/P673 which is fairly common.
Less than a half dozen are confirmed in copper with the illustrated example showing the high date.
An incomplete reverse die trial, JA1868-1/P3341 is also known.