Doesn't it just mean you can have a 2nd without destroying the 1st? Just cast again.
It means you can have two summoned or raised followers. For example, you have a flame atronach already following you, you can summon a second one, whether it be storm/frost/flame or even raise and undead follower. Twin souls is incredibly useful. Just cast your conjuration spell twice and there ya go. Enjoy.
You have to cast the second one separately. After casting the first one, you can then cast another one.
You can, just have one spell in each hand and don't duel cast. Start casting one right before the other.Thanks mate. It would be nice to cast two exact souls with one cast.