Vision of Emperor Csarth issue

[Jugganot]

After killing Emperor Csarth 3 times or so it seems the event bugs out. I kill one shard of the emperor , then i go kill the other but after i kill him he just respawns. Just wondering if this is normal or if its a bug. It might also happen when i also get other adds from normal trash spawn that agro, just incase that helps.

Thanks, Jugganot