In early 1906 the Canal Zone needed further supplies of 1c and 2c stamps but Panama Scott numbers 179 and 180 used by the Canal Zone for Scott numbers 9 and 10 had run out. As the Canal Zone did not want to have another series of double overprinted stamps Panama agreed to supply them with the 20c and 1 peso stamps of the 1892-96 Colombia Department of Panama issue, Panama Scott numbers 19 and 21, but without a Panama overprint or surcharge. This is the only time that Panama sent Republic of Colombia stamps to the Canal Zone which were not first overprinted by Panama with the customary bar and PANAMAs.
The ICC printing office set up one form with a surcharge in black with two horizontal bars to obliterate COLOMBIA at the top of the stamp and CENTAVOS or PESO at the bottom. PANAMA was printed in small Roman capital reading vertically up at the left and down at the right and CANAL ZONE was horizontal in two lines.
There were 3 deliveries of these stamps to the Canal Zone and since a different form was used each time each printing should have received a major number in the stamp catalogues because each is a major type.
