The behavior of dual centrifugal pendulum vibration absorbers (CPVAs) are investigated when they are attached to a rotor in order to suppress torsional vibrations of a horizontally rotating shaft. The frequency response curves are theoretically determined using van der Pol’s method in the two cases where CPVAs are attached at point-symmetrical positions and identical positions. In the former case, Hopf bifurcations occur and combination resonances appear at comparatively higher rotational seeds than a Hopf bifurcation point. In the latter case, two types of localization phenomena may occur depending on the stiffnesses of torsion springs installed at the supporting points of the CPVAs. These phenomena are confirmed by calculating time histories and their frequencies. It is concluded that the optimal positions of the two pendula may exist to suppress the torsional vibrations of the rotor.