I was looking at the nib units of my two Parker Duofold Centennial of the first generation, just to check that they are exactly the same, and the inner threads are equal on the two pens. And yes, they work, so I can have the nib I want on the pen I want to use. This is good, because my orange Centennial has a needlepoint EEF nib that I like much more than the M nib of my black Centennial, but I want to have also the latter in my rotation. Well, checking the combinations of pens and nibs, I just noted the black cap of one Duofold close to the orange body with the black finial of the other… Hey, but that is really like the sister of my Hemingway! Actually, both my pens are of the 1990-1991, so they precede the launch of the Hemingway by one year at least! I could not consider them a "copy" of the Hemingway, being born before ... And, if indeed a pen can proudly sport an orange body and make a bold and well-deserved reference to an American writer who achieved fame in the 1930s, this is Parker Duofold! How did I not see it before ...