Proofs, Flaws, and Specimens
It would be expected that De La Rue would produce die proofs and plate proofs for each denominated value. Indeed, as listed in Gisburn, die proofs are known in green and carmine on unwatermarked paper, and undenominated plate proofs are known in gray, ultramarine, olive, purple, and black on green on paper watermarked Crown and CA. The undenominated plate proofs are imperforate.

  

Overprint 15½ mm x 1½ mm           "Aore coll."

 Curiously, however, according to Gisburn, the only denominated proofs that are known are of the ½d value in an unissued lake color. All are overprinted "SPECIMEN" horizontally (upright or inverted) or diagonally. Three settings of the horizontal overprint are known: handstamps (according the Gisburn, but see below) measuring15½ mm x 1½ mm and14 mm x 2½ mm, and a type setting measuring 16 mm x 1½ mm. The diagonal overprint uses the 15½ mm x 1½ mm handstamp.

Exactly which of the De La Rue SPECIMEN overprint settings were used for the proofs is unclear. Samuel mentions a few that might be candidates. The 15½ mm x 1½ mm handstamp is possibly Samuel Type D9a, a designation he gives to "a small group of overprints of similar appearance but of different dimensions to Type D9." Type D9 measures 15 mm x 2 mm, but is otherwise quite similar to the overprint in the illustration above. The 14 mm x 2½ mm overprint is possibly Samuel Type D12x. If so, it was likely applied as a form to the entire sheet rather than a handstamp on individual stamps. There is no likely suspect listed by Samuel or Bendon for the 16 mm x 1½ mm overprint.
Given De La Rue's reputation for quality printing, it is not surprising that only one constant flaw has been found in the entire issue. The flaw occurs on the 2d value only. In the picture at the right, it appears as a dot in the water between the second and third rowers from the left.

Sets of stamps overprinted or perforated SPECIMEN were supplied to the International Bureau of the Universal Postal Union (UPU) for distribution to member countries to notify them of the impending or recent issue of stamps. The various printers of British Colonial stamps maintained forms for overprinting stamps in the formats they produced. These forms have been well-cataloged by Samuel. For the Small Canoe Issue, Samuel Type D12 (14½ mm x 2½ mm) was used. This form was normally used for the small, vertical-format issues widely in use in the early years of the 20th century. Therefore, the overprints read vertically on the rotated format of the Small Canoe Issue; upwards on the ½d, 1d, 2d, 2½d, 5d, 6d, and 1/- and downwards on the 4d, 2/-, 2/6,  and 5/-.
       

The number of specimen sets released depended on the number of members of the UPU and the number of sets sent to each member country. Additionally, a small stock was formed to supply future members of the Union. At the time of release of the Small Canoe Issue, 400 specimens were supplied (Samuel). Since such a relatively small number of stamps were overprinted, since the value of the specimen overprints is 50% greater than the normal issue, and since forging an overprint is straightforward, buyers should exercise care in purchasing this issue.