Actually most RRs are just two pieces of glass in each element. Gundlach had a habit of adding another glass, which didn't do much, to their designs. I believe the Radar was like that for example, and like you say the T-R lenses were.
Wasn't the Radar a Heliar clone? In which case you really would need three elements..
I have Kingslake's book, A History of the Photographic Lens. His diagram of the Gundlach Radar is identical to his diagram of the Tessar, except the Radar uses a cemented triplet in the rear group where the Tessar uses a cemented doublet. He uses the Radar as an example of how some lens designers got around existing patents that way.
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