Chemical overlap: probably there isn't--I have an inconveniently lengthy set of strong-smelling oils on my allergen list. I think it's vanilla and those together, and almond and another nut together, and soy/peanut together....

Gotcha. I am glad they are known allergens and therefore reasonably manageable. That sounds very near a list of things that people put in everything whether you are expecting them or not. (I'm not allergic to soy, but I keep finding it in places I wouldn't have bet on.)