Had to have been an interruption (maybe lunch; too much wine ?) and upon returning the engraver placed the piece in the stack/crate with the finished pieces... Also, somewhere in the process, he screwed up (?-maybe not) the registration number... The bannerette should have included CERCLE DE LA PRESSE. It is not only the error which contributes rarety, but the fact there are no other known pieces of the denomination.

ChipGuide image.