I used to have a surround system which would bring out parts in songs I never realized were there.  For example the Red Hot Chili Peppers song Falling into Grace would have the backing vocals really loud coming out of the surround speakers.  
 
Is there a way to split a track like that?
 
I have used sound editing before that splits into the left and right channels but can you split into more.  
 
I think this lies in Dolby piggy back elements as this was from a CD and not a 5.1 dvd or anything.  

(AFAIK) As a normal audio CD can not have separate 5.1  or any other than a stereo track , it is, as you suggested, your 5.1 amps DSP circuit that moved the vocals to rear speakers even though the track is a normal stereo track. It's not a split track or anything like that.
 
I don't now how much you can pre calculate what your home theater system does to the audio. It could be very different in different FX modes (Cinema, Adventure, and whatever there are) and on different amps. Hit and miss, I guess (??). Unless I'm just left behind and there are techniques I know nothing about.

Thank you for your reply .  I was thinking that mp3's would lose something that the actual cd would be capable of but as you say there are only the 2 stereo channels that are manipulated.