Minecraft plays two or more music songs at once.

When past the launcher and on the menu to select a world to play, Minecraft will play its normal song. When you enter a world, this song continues to play, as opposed to stopping and playing the music from inside the world. Then, once you are inside the world you get two or more different songs playing on top of eachother, as if I had a few copies of Minecraft open. It is quite frustrating. Any ideas?