Something just popped into my lil brain-I separated two cars for a mod-duplex setup. You didnt notice that one car was not canceling a hall call on one floor. The other car would pick it up. When I took out the first car for the mod the second car would go to the call and not cancel it. Being two four stop units it was never noticed with both in operation. I found that we installed a dispatching update in the early 80's and that the second car was lacking the UHST from the dispatch upgrade to the selector, only at that floor-the wire was never installed
