Ender Dragon in monster spawner is duped and glitched

Ender dragon in spawners are weird because it dupes It and one is weird.

 

How to recreate:

1. /Give @s ender_dragon_spawn_egg
2. Put a spawner down and the spawn egg in it
3. Ender dragon is glitched

What it should look like:

1 spinning ender dragon inside spawner

What it does look like:

1 ender dragon in spawner and another one outside