Hey!
Indeed that is a bug. I spent a little while going through that sequence to try replicate what you encountered without luck initially, but on loading from a save into some of the scenes it would play audio from a previous scene for some reason, even if it was not there when saved. I'm not sure why it would do this, perhaps something in Ren'Py itself when I updated it a little while ago and didn't notice or something I did. One thing I also noted is, it only does this for sounds that are played within a video file, even though the video isn't playing, so I could separate the audio from the video if I have to. I'll try find a fix for it asap.
EDIT:
Looks like the first thing i tried, updating the engine to the newest release of Ren'Py fixes this issue. I'll test it a few times to make sure nothing else breaks from the update and release it soon as I'm confident it's fine.