Three appear to be philatelic usages from a single cover, as they bear identical markings on the same date (items 1a., 1b., and 1c.). The fourth copy (1d.), referred to by Schlieper as the Kilian copy after its owner at that time, bears a manuscript cancel of 7 October 1911, and a subsequent Rabaul cancel. Of the four copies, this is the most likely to be genuine, as mail from Namatanai would have been routed to Rabaul, where a proper cancel could have been applied.
The manuscript cancels were written with ink containing iron using a steel pen. The handwriting on the four copies appears to be the same, lending credence to the belief that they are legitimate contemporary usages.
Two of these copies (1a. & 1d.) are in the GermanStamps.net Collection.