I'll see if I can explain this so you can reproduce it.
Create a smart list as follows: lastplayed=<=86400
This will show only songs played within the last day. This works.
Set the playback filter to skip this smartlist.
Go into Media Library and start playing X. X will show in the smartlist. Before X finishes playing, start playing Y. You'll see Y in the smartlist.
Now hit Stop. You'll notice that the icon for X and Y isn't faded.
Start playing X again, it plays (not supposed to), same with Y.
Now play either X, Y, or a new song (Z) and let it finish (or move the slider toward the end to finish)
Once it finishes, X, Y, and Z are updated and won't play (like it should)
If you do a restart, they get updated aswell.