What I expected to happen:

• entity.player.hurt only plays when you take damage
• entity.player.death only plays when player dies. It does not play with entity.player.hurt

What actually happened:

• entity.player.hurt plays with entity.player.death

To reproduce:

1. In a creative (or survival) test world, run /kill
2. Player dies with duplicated sounds
3. Turn on subtitles for more obvious results

Notes:

As far as I'm aware, this isn't present in the 1.15.2 releases.