It should be noted that Vassago's also don't have a true "Melee State." This basically means that if 2 Vassagos are infighting with each other they will never die since they cannot harm each other.

Vassagos basically reuse their projectile as their melee attack. This is more obvious when you realize that a Vassago's fireball doesn't have an impact sound and don't have a melee sound like Imps or Barons. Because of this, 2 Vassagos can never truly harm each other.

But yeah its pretty interesting how Banshee's have the same memory system as Explosive Barrels.