That's a great question and a very honest question. I felt the same way when I was in college and completing classes towards my core requirements. When I look back at it now, I'm actually mad at myself for not caring more about those type of courses because I know I could have done better and received better grades but hindsight is 20/20. When you don't have a strong interest in something, it's extremely hard to stay motivated. I always felt if it wasn't something that wasn't going to impact my future career than why should it matter. Now, I feel like having that information would make me more well rounded.
Since these two classes are providing you with coursework that you are already aware of, try talking with your professors and ask them if there is something in further detail that they can provide for you to help you further your knowledge base. You know how people say, that you have to be your own advocate when it comes to your healthcare? "Make sure you ask your doctor lots of questions." I think that statement applies when it comes to your education also. Push your professors to provide you with material that will challenge you. Chances are they will be grateful to have someone show extra interest!