"Should I avoid overlap between essays? My essays contain different information, but they both seem to highlight my passion for the same academic interest. Is that bad?"
Yes, you should avoid overlap between essays. When you're writing a sentence, you don't write 30 words when you can make the same point with 15 words. When you're writing an essay, you don't include 5 examples about how soccer made you a better person when you can make the same point with just 1 example. And when you're writing an application, you don't write 2 essays about the same part of your personality - like an academic passion - when you can communicate the same message with just 1 essay. Each word, example, and essay should reveal something new about you.
If you insist on writing two essays about the same topic, make sure each highlights a different part of who you are. For example, suppose your academic interest is biology. The first essay might focus on intellectual vitality - how you developed your interest, how you explored your interest, why biology fascinates you. The second essay might focus on teamwork - how you worked with other people in a lab, what surprised you about working with other people, how the experience changed your approach to working with people.
Remember, many of the "Is this a good topic?" type of questions miss the point. There is no golden ticket topic that will get you in automatically. As a wiser person wrote, "There is nothing new under the sun." Admission committees have seen every topic you can imagine. With rare exception, how you treat your topic matters more than what topic you choose. The topic is means to an end: revealing your personality.
Good luck writing!
Jon Perkins holds a B.A. in English from Stanford University and a J.D. from Harvard Law School. He helps students with their college, law school, and medical school applications.