No questions are stupid! No they are not unique cultists. There are five unique cultists in the encounter deck, but I won't tell you where the sixth one is as it will spoil your game ( assuming you haven't already played it). The five unique cultists have the 'unique' indicator just in front of their name.
I was confused by ‘unique’ as well, but fortunately realized my mistake after killing first really unique cultist. I think the problem is that the word ‘unique’ is used too casually, so people think that it simply means 'different'. May be it should be bold to emphasize that it is a game term and implies cards with (*) in their names.
I think it is buried somewhere in the rules reference, that "unique" cards are marked with *. As FFG does this with every LCG that I have seen from them, it was pretty obvious to us. If you haven't thrown as much money at them as I have, I think this is a totally valid and good question!