This has been a bug for a while now, after playing the game for a while, two music tracks will play simultaneously. Creating a terribly ear-raping bunch of noise. It gets really bad, and I'm surprised it hasn't been fixed yet, does Uber not know of its existence?
Yes, one reproduction that works almost universally is when you scroll through the chronocam tracker quickly. Other than that it just kind of happens after a long game (30 minutes +) It occurs in multiplayer and replays, I haven't seen it in G.W. though. I am using mods, but it does happen without them.