Discovering new music? We7 & Spotify streaming
 

Don Pearce wrote:

That would only make sense if somebody was listening absolutely
synchronously with me (to some early John Mayall, I think). I doubt
very much if that was happening.

My guess is that someone had the music you were listening to in their
queue. It does use buffering (start playing a track, wait a few moments,
and then skip forward a minute or two and you'll see what I mean).