Why can WebAudioSoundManager have duplicate keys?

Phaser 3
1

What is the reason WebAudioSoundManager can have multiple sounds with the same keys? I would have expected it to work more like TextureManager.

this.sound.add("key");
this.sound.add("key");
console.log(this.sound.sounds.length) // 2
2

The sounds in the audio cache (this.cache.audio) are unique. But the Sound Manager isn’t a cache, it’s more like a player, and sounds added by sound.add() are like tracks. You can play overlapping tracks with the same key (source).