your right,except on an English, if your playing in e flat or a Flat,these notes are duplicated on both right and left,and you can do the pedal effect between these two chords as an eflat note occurs in both chords,definitely more scope on the duet though,thanks that is useful information.
with an english,you can use the pedal effect,lets say your going from c major to f major the c note has to be played an octave higher,lets say on the right hand side,and can be held onwhile you play the a a third below and the f a third below that