USA: (Sc544 & Sc545) (Sc596 & Sc594) (Sc613 & ?)

There is no equivalent Harding Memorial stamp to #545 and #594 because no coil sheets were produced for the Harding Memorial stamp, so there is no "coil waste" from which to produce an equivalent stamp/listing.

There is a "tall" stamp and also a "wider and shorter" stamp for both the Washington and Franklin stamps you mentioned, because both stamps were produced as vertical and also horizontal rotary press coils. These coils were made from separate rotary plates (one rolled end-wise and the other rolled side-wise, so the dominant stretching will be in different directions). Since the Harding Memorial was never produced as a coil, only one direction rotary plate was made (producing a slightly taller stamp) -- that is why I stated there is no 2nd listing to match the rotary sheet/coil waste listings you mentioned in your original post.

You can show a "wider" stamp (using direct comparison, please no ruler pictures), but it's just wild guesses as far as what might have caused that anomaly.

To distinguish between the 4 major Harding Memorial varieties, the design width is not taken into consideration. There are several factors that must be met (not just height of stamp design). The 4 varieties are distinguished by the cleanness/sharpness of print (flat vs. rotary), the noticeable height difference (flat vs. rotary), and the perforation (perf 11 or perf 10). All three criteria would have to be met, AND be convinced it's not a perf/reperf alteration of #611 or #612 (see the listing snippet that Beryllium Guy provided).

Not being able to rule out something might have happened, doesn't prove that it did happen. You have to be able to find historical documentation of a different plate/run to prove it happened. You cannot simply say they did something off the books or covered up a mistake. Yes, they do make mistakes, people go back into the records/correspondences, and find out what happened. But you do have to do the legwork.

Production variations occur during the rotary wet printing process of that time. This invariably will create some unintentional production variations. But mostly, just typical variations that are considered normal, but not significant enough to warrant detailed catalog listings.

But if you are suggesting that they might have created a another plate with wider stamps, you have to be able to find documentation supporting that. It is expensive to make a new plate. By the 20th Century, the BEP was giving each one of the plates a new number. These are all well-documented. There are examples of plates produced but never used. There are examples of plates used, but for which stamps printed from that plate/position have not been found. It's unlikely that you have found a plate that was never documented or that nobody in BIA (now USSC) noticed in the records. BEP kept pretty extensive records. The British kept even more meticulous records, recording creation/evaluation/test/start/stop dates for each plate from the Penny Black onwards.

Well we haven’t seen this mystery stamp so far …. So how about showing what the discussion is all about .

I know exacty what you mean and I agree with you .... our New Years Eve was last night and I aint doing no legwork mate, cause my legs areactually killing me right now what a big night we had here .....
HAPPY NEW YEAR TO ALL

Unlike flat plate press, the rotary press plate must be rolled like a cylinder. To change the direction, for example produce a horizontal coil instead of a vertical coil, you would have to make a new plate and roll it in the perpendicular direction. That's why I said if you have a wider stamp, it can only be a natural production variation or something happened to the stamp after it was sold. Not something intentional. The production of another rotary plate is not trivial.