Double eyepiece holder for two person observing is described in the attached catalog.  It was available in a Model A for .965″ eyepieces and a Model B for 1.25″ eyepieces.


This is one of the early advertisements for the Duetron (October, 1959):


Photos courtesy of Xavier Debeerst

unitron_duetron01 unitron_duetron02 unitron_duetron03 unitron_duetron04 unitron_duetron05 unitron_duetron06 unitron_duetronA01 unitron_duetronA02 unitron_duetronA03 unitron_duetronA04

This second set of photos is of a 1950’s unbranded version of the Duetron Model B.  This is the larger Duetron for two 1.25” eyepieces.  It has a chrome finish and includes a blue filter for the second observer.

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Some additional photos of a Polarex Duetron Courtesy of Stephen Brennan:

Polarex Double Eyepiece Holder - 1 Polarex Double Eyepiece Holder - 2 Polarex Double Eyepiece Holder - 3