A new approach to prepare and characterize prestressed competitive double network elastomeric systems was investigated. A styrene-butadiene-styrene (SBS) triblock copolymer system containing physical cross links was used to a:thieve a double network by additional chemical cross-linking using ultraviolet (UV) light. Properties measured from conventional monotonic tensile tests, stress relaxation, thermomechanical, hysteresis, and swelling analysis were investigated and related to their network structure. These double network elastomers show a transition between competitive and collaborative behavior in their mechanical properties at different strain regimes. These elastomers also show lower permanent set in both low and high strain regimes along with lower hysteresis. These networks exhibit lower modulus along with lower coefficient of thermal expansion, still slowing lower swelling ratios, which results from a competition between the networks.