Yamaha DTXpress/DTXplorer/DTXtreme

hello all,
            i have recently been playing around with the gm voices in 
my module via- a midi keyboard and have come up with some cool 
stuff,my question is if i recorded a track on the modules sequencer 
can i change the voice of the second track i want to record (this 
will be another keyboard track) without changing the voice on the 
first track that i have allready recorded?????????? an example would 
be i have a piano track,and i want to add a synth part to it on the 
second track

thanks ,
         sam(otacon28)