Here are two stamps that would not exist except for the overprint, these were part of the U.S. special printing program of Julu of 1875.
The first printing of the 1 cent values of four departments, Agriculture, Executive, Justice, and State having been sold out, a second printing of those four stamps was made and delivered on 12 31 1875. These two printings were of 10,000 each.
Sales of two of those stamps continued to be brisk and by 1881 the 1 cent Executive was againg sold out, and a third printing of 5000 was ordered and delivered on 12 31 1881.
Six months later the supply of the 1 cent state was running low and another 5000 were ordered and delivered on 8 31 1881.