This card is an unusual sort of animal, for which at present I am aware of no peer. It appears to be the result of the press ink well going dry and the card being printed with only phosphorescent taggant. I don't know the technical details of the potter hoe press on which this card was printed, so I can only hypothesize. The card exhibits a couple pinpoint dots of the regular green ink color in the vignette, so I guess it's not a "purist's" color-missing error.
This example may, in fact, be a unique survivor. The backside exhibits preprinting which indicates that these were used for utility bills. How many customers saved their stubs?
Place mouse on image to see the reverse side of the card.