That's cause propagation is constantly changing and that way they always have a frequency to corrupt u with..
Back in the day, Radio Moscow in the evenings to North America may have been on as many or more than 15 freq's simultaneously - 49, 41, 31, 25 and sometimes 19 and 16 meters when the sunspot cycle was high, like late 60's or early 80's. A lot of freq's on 41 meters...Radio Moscow rendered the 40 meter Amateur band nearly useless during North American evenings. This was in the day before operations began above 7300 kHz.
It's to my understanding that the radio moscow most often heard here was actually from Cuba..
Not at that time! Cuba did not even have enough transmitters for their own Radio Habana Cuba let alone give any air time to anyone else. The propagation was almost always such that the signal was multi-hop, lots of fading. The signal from Cuba is one, maybe two hops, so any transmission from Cuba would have been a more reliable, fairly constant signal. Really doubt few, if any Radio Moscow programs were relayed back then from Cuba...
Have you ever listened to radio Cuba, they play killer music, and have great salsa, cumba, and jazz music, but also an american accented man trying to corrupt you into liking fidel....lol its funny,
Loved the music, changed the channel when the propaganda came on!