If you mean 2 note lanes running at the same time as in they way it is possible in reason 4 then no it is not possible, if you have notes playing at different times then yes it is possible, all you would do is automate the volume level but it is not possible to have 2 seperate volumes if notes are playing at the same time, you could adjust the velocities on either track to make a difference but this will only apply is the patches you are playing are velocity sensitive !
Your best bet is to open another synth copy your notation to the track and then you will have cntrol over the 2 volumes seperately