Honestly,this just seems like the evolution of T206 collecting to me. What with premiums for scraps, ghosts, missing colors, added colors, stray dots, missing dots, overprints, underprints, brown backs, brownish/blackish backs.
Always looking for the next big what if, or variation. Seems as if it was only a matter of time before somebody came up with something like this.
Any other set it would just be a miscut or off-center curiousity. Looks like you T206 guys just got what you were asking for.
.........and I'd wager whoever this "consignor" is, is most likely one of these advanced "collectors" you all know and love.