Zagan and Haagenti, dual diagnosis

Howdy.
In case it wasn’t glaringly obvious, Haagenti and Zagan (Zagam) are practically the same in their abilities and appearance. They both very much represent the alchemical nature of the universe.
I’m planning on evoking both daemons at once, perhaps to give a sort of reinforcing effect to my requests and personal gnosis.
Is this a thing? Does it make any difference? Haagenti alone was incredibly instrumental in kicking my 30-year cigarette habit, so I’m not even sure if invoking both at the same time is even worth the effort.
Any opinions on this? Does anyone have experience invoking multiple spirits simultaneously?