Bimodal magnetic behavior, in which Kerr rotation (theta(K)), and ellipticity (epsilon(K)) each exhibit major magneto-optic hysteresis loops with two distinct field-dependent steps, was encountered in a (0.3 nm Co/1.2 nm Pt)(15) multilayer film with perpendicular magnetization. A model is postulated in which there are two different interacting magnetic entities present in the layered structure of this material, each with a stable perpendicular magnetization state either parallel or antiparallel to the applied field, and which reverse quasi-independently from one another. Due to interactions between the two, the reversals occur at the intrinsic coercivities displaced by an interaction field, H-i, whose sign depends upon the magnetization of the other phase. Using major loop and,first-order reversal measurements, the intrinsic coercivities, as well as H-i, were obtained.