A device for heating a hydrocarbon resource in a subterranean formation having at least one pair of laterally extending upper and lower wellbores therein may include a radio frequency (RF) source. The device may also include an upper wellbore RF radiator to be positioned in the laterally extending upper wellbore and including a plurality of first terminals. The device may further include a lower wellbore RF radiator to be positioned in the laterally extending lower wellbore and comprising a plurality of second terminals. The device may also include an interconnection arrangement configured to couple the RF source and the first and second terminals so that at least one of the upper and lower wellbore RF radiators heat the hydrocarbon resource in the subterranean formation.