These were issued in sets along with the one cent J666-J667/P741-P744 and 5 cent J684-J685/P763-P764. To view the set, click here.
These were struck from two reverse dies as follows as shown at the bottom of this page:
Nickel with short dentils and low wreath on reverse J676/P753 and is the example illustrated above and the first image below. It is fairly common with several dozen known.
Nickel with long dentils and centered wreath on reverse J676/P755 and appears to be far rarer than the first. It is the second example illustrated below.
Copper J677/P754 or P756 It appears to be unique in copper and hasn't been seen since Kagin's 5/57 sale. It is not known which reverse die it has.
Photos courtesy of Saul Teichman