I've played through all of the New Vegas DLC. There are a few missing songs on the Mysterious Broadcast station. The only song I know the name of is Begin Again, which oddly enough, did not play once during Dead Money. I may be wrong, but I thought there was a part during Dead Money where that song was played.
Anyway, unless it's all coincidence, I'm only getting 3 or 4 songs to play on the mysterious broadcast. There are so few that it wasn't uncommon to hear the same song 2 or 3 times in a row.
I have not installed any mods that would change the radio or it's stations. I just want to know if anyone else is having, or noticing, the same thing. I'm not asking for people to go and look for the problem themselves. Just play the game, and if you notice anything similar to what I experience, or know of a fix, please let me know.