Mmmmmm.......Doubling effect. Ive heard you can copy your voice track into another track and detune it.A heavy chorus might yield a similar result. If you did the dual track copy and detuned one track and then panned one hard left and the other hard right. My cakewalk program also has a harmonic funtion that allows you to do mostly the same thing. If by doubling you meant some sort of a slapback effect, that is pretty easy to achieve in most delay effects.