The 1945 Omas Colorado double-barreled vacuum filler qualifies as an extraordinary pen! It is a double-nibbed pen with a scissor barrel configuration (below: pictured open). Each section is marked with a red dot or a white dot to identify your inks and tell them apart. The pen is black with nickel-plated trim. Closed, it certainly looks like a pen but in its open configuration, it’s tricky. The nibs are medium/fine.
Orlando Quadretti has been credited as the inventor and maker of the Colorado, of which the first prototype was handmade in 1936 by Orlando Quadretti. The idea was to create a pen that could use one red ink, one blue ink, for bookkeeping purposes, and without having to change pens between entries. Unfortunately, the Colorado was not produced for very long.
Find it for $2300 in Catalog #72. This specimen is in near mint condition.
Source: Penna Magazine