Whats wrong with my freerecorder?

Ok so i downloaded freerecorder to obviously record songs off spotify
but ive had a problem. It seemes to record two seperatel layers of the
song. If that makes sense. Like for instance a song "The fire" by The
roots. when i start recording it follows the sound levels of the
backing with a blue line and the rest with a yellow line.

The problem is it saves these sepaeratley, so i can either listen to
the backing, or the rest of it. Not all together.

How do i solve it so it saves them both as one, or if not how do i
merge them?