Two music pieces playing at once

I was wanting to play the music 'cat' and so used /playsound cat [my username]. Cat started playing. However, as I continued to listen, another piece of music started playing too, which I think was far but I'm not entirely sure. These two fine pieces of music were playing at the very same time and so didn't sound fine at all. Since then, music always seems to play at the same time. However, The music playing at the same time may not have been triggered by me using the command /playsound cat because it was the first thing I did once I had updated to 1.7.2.

I expected to listen to cat and have no other music playing at the same time.
But what actually happened was two pieces of music played and this always happens.

Steps to Reproduce (These may not be entirely accurate):
1. Force update minecraft.
2. Use the command /playsound [music] [playername] .
3. Listen.