Have you ever tasted or served a dessert that smelled like the garlic you used in the main course? Say you're roasting a whole fish at the same time you're making a pound cake. Certain spices and foods are so strong that their odors permeate everything else. So you have another time logjam, waiting for your oven to "air out" so you can put in the next dish.
With a double oven, you avoid this dilemma altogether. Your garlic chicken can cook comfortably in one oven while you bake mouth-watering brownies in the other.
It may seem like a small benefit, but whether you're a cooking aficionado, a detailed-oriented person, or if you just don't want your peanut butter cookies to taste like pesto, you'll appreciate this benefit of the double oven.