Ideas
This bug does not happen randomly in my experience. It only happens when one loading-screen track has finished at the same time that the lot has finished loading in. So one track concludes and the game loads both the lot it was loading as well as the next track for the now-finished loading screen. When that happens, apparently there's nothing in the game's code that tells the track that it can stop, so it keeps playing until you quit the game and reload.
The timing for this is really tight, so most of the time you don't have this happen, and when I time my loading screens to avoid those transitions between tracks, I have never had this issue pop up. I don't have any saves handy without mods to share, but it would not surprise me if anyone could find this bug with some tedious testing.