Did Muse copy when they wrote the Exogenesis Symphony?

As a devoted fan should be, I love my favorite band with all my might and stick up for them. But the other day I was in David's Bridal, and they were playing Orchestra-type music over the speakers. Well, one song faded into the next, and I started humming along. I thought it was just another Beethoven song that everyone knew. But the more I listened, the more familiar it became, and then it hit me: it was Exogenesis: Symphony Part 3 (Redemption). I was VERY excited that they were playing a Muse song, but then it became more advanced, and there was no singing, and after a LONG time, it faded out and into a new Symphonic song, like it was a CD of just orchestra music. So what happened? Like, did Muse copy from another symphony, or did this CD just asked to play just the symphony part of it? I KNOW it was Muse, for I began singing and dancing with it in my changing room and knew every word and key.