The overprints were said to be done to a lack of the 2c and 8c stamps at the time. The first printing had 3.5mm between the lines of surcharge. A second printing was made some years later with the space between at 5mm. Again with NB stamps, the reasons for doing so are unknown except to serve a philatelic purpose. The "8 cents" surcharge was made purely for the pleasure of collectors as there was no need for a stamp of this denomination in 1892 when the international letter rate has been reduced to 6c. It is relatively uncommon as apparently only 300 stamps were overprinted.