I can hear one or the other (not both at the same time). With me it depends on the hour of the day. And I discovered this trick, not entirely sure if this will work for you, so YMMV.

If you hear "Laurel", close your mouth and pinch your nose with two fingers. Next try and give a big breath out. Because your mouth and nose are closed, you should feel a "pop" sensation in your ears. This is somethiing I do everytime I do after a flight.

Now listen to the video again. Do you hear Yanni?

I suspect this has nothing to do with age at all, just different pressurisation around the ear drums giving this audio illusion.

Nope, did not work. Tried everything, popping my ears and listening, popping the ear while listening… I will try maybe later tonight…

There goes my theory. But at the end of the day this is an audio illusion. With Hifi, if you can only hear "Yanni", you tune and tweak your audio system to give you the most beautiful rendition of "Yanni". Ditto if it’s "Laurel", or both.

At the end of the day, music playback is also an illusion. Know what you can hear (i.e. your strengths) and maximise that. This is the only way to improve the audio rig. Absolutely requires the human touch, can’t do this with measurements.