Spotify changed the version of Vacation in my years-old playlist

I've had the original version of Vacation on a Spotify playlist for years now. But today, listening to the playlist on normal shuffle (none of that smart shuffle nonsense), the version with Train comes on, which I didn't even know existed until today. I can re-add the original version to the playlist, but the version I added years ago seems to have changed. Super confused... has this happened to anyone else?