Duluth, MN-Superior, WI is also a mix of K and W stations.
Was thinking ... In the earlier days of radio (like way before my time), if people were more likely to listen to out-of-area stations (maybe out of necessity due to the content they wanted not being available locally) ... could there ever have been times when a C, a K, a W, *AND* an X would have all competed with each other if, for example, you lived in some place like Colorado, Nebraska, etc?
Or what about one competitor being so similar to another (like major programming overlaps -- for example I had been thinking of not only having the same playlist, but playing the songs AT THE SAME TIME, but was realizing that there's issues with that scenario ... but at least some significant similarities), so that one station actually took legal action against another (regardless of the outcome)?
Or, for the DX side of the equation ... would it be theoretically possible (assuming the stations were at the highest powers they've ever been, or still on the air - I know some Canadians / Mexicans have since either reduced power or gone off the air) for co-channel C and X stations to compete on groundwave, with a sufficiently sensitive radio & antenna/ground setup at the receiving site? Or, what about, on skywave, a C and an X station competing with each other on the same channel that has a K and a W in states that have a coastline?
There is nothing that says a station can't play the same song at the same time as another station. Usually it is by coincidence, not intent. It can happen occasionally today with high-rotation formats like CHR, Country, etc., where songs play every 90 minutes to two hours if they are in power rotation and if there are two or more local direct format competitors.
I remember reading, probably on this board, about overnight jocks at competing stations who were friends away from work and would amuse each other during their long, boring shifts by phoning each other with tips on what's playing next. They'd parrot each other's playlists for a while and hope the boss wasn't listening. He usually was and quickly put an end to the nonsense.
I remember during my college days listening listening to KOMA, and once in a while hearing WKBW underneath playing the same exact song. I think it was a random occurrence on two tightly formatted top-40 stations.