This is still happening and yes, it's extremely annoying.
I find I need to take time out of even my bullet games to shut these extra tabs if I forget to do it before the game.
Common practice: play a game. Pick analysis. This opens a new tab. Finish analysis -- start new game in that tab. Now chess is playing in both tabs, with a sound delay.
I don't understand how you haven't fixed this problem it has been for ages.
If ther are multiple chess.com tabs open, then any time a sound is made in one tab, it is "echoed" in all the other chess.com tabs. Very distracting and annoying.