Check if sound has already been added to the SoundManager

[PicoFoundry]

I was wondering if it was possible to check whether a sound has already been added to the SoundManager, so it is not added a second time. I did not see anything in the documentation that indicated whether this could be done. I have a number of menus as separate states, and want music to continuously play over all of them. Currently, I start the music in the main menu, but when I return from a submenu it starts another instance of the sound.