The trace on your tracking generator looks like what I see WHEN tuning duplexers. The funny thjing about commercial/public safety vhf is the spacing between input and output of repeaters is not a standard. Unlike hams , the frequencies are based on availability in an area within the channel use alolocations.
In other words they can be all over the place !
You have to tune your duplexer for peak and notch for the channels you have been assigned and licensed for. Not for a fixed spacing like hams and UHF services have.
Generally the big threaded rod sets the pass (fairly broad) and the little one sets the spacing, mostly where the notch is (very critical tuning).
FISTS #3853,cc 455
SKCC # 1395,tribune #12
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