Do orders stack?

I know of 2 orders:

Order of pain and Order of vampire

If i use them both (15 each) will they cause 30 dmg or still 15?

Perhaps reading the descriptions closely will tell you the answer?

im reading details but im still not clear with it?

k i think i got it

The whole "...whenever a party member who is not under the effects of another Necromancer enchantment" should give you a hint

Plain English: Order of the Vampire only works when they have no other Necro enchant on them (IE: the other orders).

they nerfed them a while back not to stack