A new dimer model is introduced to describe the behavior of dimeric processive motor proteins in general. A single motor domain is modeled using our previous work on hybrid motors that exhibit elements of both a powerstroke and a Brownian motor mechanism. The different behavior observed in Myosins V and VI can be explained by varying the physical parameters describing the coupling between the two motor domains. The dynamics of the resulting stepping mechanics under loaded and unloaded conditions are examined. The results from this dimer model are compared with experimental data for two-headed processive motors.