Music Glitch - Multiple Tracks Being Played at the Same Time

When I was playing 1.7.2, I was building something, C418 music started playing. I continued building, then I heard something odd. Another C418 song started playing at the sametime the other song was playing. Then after that, up to three songs were playing at the sametime. Also, even when a track is already playing, you can play a music disc at the sametime too.