My dear creation kit expert, i am trying to create a choice between two perks, you can't take both of them, but only one of them. Can you help me? Is possibile to do such thing? My thanks for your patience and help!

Sure, just give each perk a condition for the player NOT having the other perk.

Oh my god, you are right, i am a walking idiot, the solution was so simple! Dumbest question ever.