Very rare. Doubling throughout design, from scrollwork to all text, to portrait. Were it not for the fact that the doubling is in different directions, this could be mistaken for a double impression.
I asked Richard Friedberg about it and he said:
It is a late-state reentry of the R13 die (Mike [Morissey] thinks likely 1870 or so) and that it was promptly corrected when someone noticed the weirdly inked stamp on each sheet. He said his (this may be the one you purchased) is the only one he had ever seen. I have one other, as you know, and a collector in Texas told me he has one. I don't know of any others. When Dick Celler, a widely respected plater from NJ, saw this stamp he said "this is a great example of really crappy work."