My 127 KL lens has two cable release sockets: one for the shutter for the mirror-up operation (the mirror goes up on depressing the release button on the body
I have the 50,65,90,127,150SF and 180. None have two cable releases. The lens has one, the body has one. The body is hit first so you eliminate mirror shake, then you release the lens shutter.
I don't have a 37 nor a 140, nor a 250 so I cannot be 100% sure but I think you mis-remember.
I haven't looked at this thread for a while so glad to see I wasn't going mad as I was beginning to doubt myself. I still think this feature of the RB67 K series lenes is a good advantage over other models but maybe not such a big deal to some users.
Still love my RZ though and will never part with it