First stage clone chart

[Paladin]

Expanding your photo a little more reveals:

Coltri sub C9000
OMS R-251
SEAC Sub Sorius
IST R-50
Aquamundo QR-5

Patent number: 5139046.

You can add 123Scuba's two first stages to this list.

http://www.123scuba.com/c-scuba-diving-regulators.html

 

[Fishpie]

.....also used by Chochran and Abyss Dive System.