Why do people run 2 Necromancers?

[Gnartar]

I'm new to the hobby and I was wondering why people run two necromancers on lists? If you can only cast each spell once per turn it seems like a waste to have two guys who do the exact same thing.

[HiveFleetCerberus]

You take two necromancers so that you have more heroes, and because each one knows Arcane Bolt, Mystic Shield, Danse Macabre, and one spell from the lore of deathmages if you run a legions list. 

[RuneBrush]

Because of the new spell lores you get quite a bit of choice each turn in what you want to cast.  A second Necromancer also gives you an extra unbind and two more Deathly Invocation rolls which keeps your army going that bit longer.

[Takaloy]

partly due Lords of Sacrament battalion, also given that they're annoyingly 110 points each, taking a second one is equivalent to 100 points (as there's nothing that is 10 points)

[grungolah]

Because one gets lonely.

[Vortumnas]

Because overwhelming dread and fading vigor on the same enemy unit is amazing! And taking a third for spectral grasp is awesome for board control too!

[Josh]

because death magic is one of the best attributes death holds

[ianob]

More than just the spells above, too:

 

Theyre hard to kill compared to other heroes, so keeps your Deathless Minions + Rezzing around longer.

6” for the above two abilities is a small range. Being able to spread it out is very important. I should have written this one first as it’s the most important - more important than access to spells even.

Redundancy for Vanhels Danse, an important spell for us.