I can't speak for your prospective program advisor (which you should contact with these questions btw) but, it generally does matter from whom the letters come from, professor or otherwise. A professor was only one of my 3-4 LOR authors. Why? Because a class is only one setting through which a person gets to know you. As you might imagine, it limits their exposure to you as a person. If you think your second professor has a different take on you than the first (e.g. you worked with one as a research assistant and was just a student for the other), I might advise you to go ahead. It really comes down to your relationship with them.
In general, it's best to include LORs with slightly different perspectives on you as a person to round out your persona. Find someone who is passionate about you not only as a student, but as an employee, leader, and/or human being. The idea here is to stand out from the hordes of applicants who all have letters claiming "Johnny/Jane is a good student! One of my best!" There will be lots of those, trust me. Definitely include an academic LOR, but I recommend using your remaining letter(s) to flesh out the other great things about you that you'd like the admissions staff to know, besides the fact your a good student and you don't beat up your classmates. 🙂 Best of luck!
Pacific University (accepted)
class of 2012