OUR NUSTAR OBSERVATIONS OF TWO MASSIVE COLLIDING WIND BINARY SYSTEMS PRESENTED CLEAR EVIDENCE OF HIGH-ENERGY NON-THERMAL EMISSION WHICH PROBABLY ORIGINATE FROM INVERSE-COMPTON (IC) OF STELLAR PHOTONS BY HIGH-ENERGY ELECTRONS ACCELERATED AT THE WINDWIND COLLIDING (WWC) SHOCKS. HOWEVER THE OBSERVED EMISSION IS NEARLY CONSTANT UNLIKE THE WWC THERMAL EMISSION AND THIS IS NOT EXPECTED FROM THE STANDARD IC MECHANISM. TO UNDERSTAND THE EMISSION MECHANISM WE NEED MORE COLLIDING WIND BINARY SYSTEMS WITH DIFFERENT STELLAR PARAMETERS. WE PROPOSE TWO NUSTAR OBSERVATIONS OF ANOTHER COLLIDING WIND BINARY SYSTEM GAMMA2 VELORUM WHICH SHOWS SIGNATURES OF WWC X-RAY ACTIVITY AND HAS A GEV GAMMA-RAY COUNTERPART TO DETECT HIGH-ENERGY NON-THERMAL EMISSION.