Apart from the resistor I see no difference. Of course you pull the zone off a dual zone tom when you make it into two mono single zones, using a y cable. As in the manual "In addition ,users can add up to four single-zone pads to their kit via the Kick and Tom inputs. Pads that were multizone initially, become single zone when their trigger input is shared."
Can you set a split Roland input into two totally independent inputs and layer multiple MIDI notes on both those inputs ?