Is it possible in the Graph Editor to select keyframes from different channels that are stacked on the same time and value? I have tried box select, various shift-select combinations, the k and alt-k hotkeys for column select etc. without success. It doesn't matter if I have all my channels selected, I can only select a single key. This is really a problem for my workflow-- but perhaps I am missing something obvious.
On the left I've made all 3 channels active-- on the right after box select only one channel and key have been selected.