What make you suspect the cancel? It appears to be ink mixed according to the then current formulas, as the linseed oil stain on the back shows. The marks on the back could be sellers notes.
There is another possibilty. It is known that Continental Banknote Company used several differnt papers in the printing of their stamps. This stamp may have been printed on one of those papers, although it does look like "thin, hard paper", it also shows the characteristics of a Continental stamp, like the clear sharp image and the well defined perfs like a Continental, having no fibers on the tips.
I have what appears to be a soft paper Continental Official, an O8, the 24C Agriculture. It shows the mottled effect of soft paper when held up to the light, and the face shows spotty inking like soft paper does. The back of my Soft Paper? 24C Agriculture has several different owners marks.