spell stacking

[wotdlois]

Quick question - do multiple spells of the same kind stack when cast at the same time?  So if i cast multiple chill fog's from either the same caster or two different companions do they stack or do they cancel themselves out?

[Althernai]

Chill Fogs stack even when you use the same caster.

[wotdlois]

Chill Fogs stack even when you use the same caster.

thanks!