I'm actually wondering this myself. I currently have a 32"x32"x63" tent and was using a 150w hps light. I just bought the Mars HydroSP150, and I plan to use them together. I'm a week into flower.
sURE, YOU CAN USE BOTH. i HAVE FOUND THAT USING hps ONLY SEEMS TO GIVE LARGER BUDS AND FASTER FINISHING PLANTS, BUT RESEARCH INDICATES THAT THE BLUE SPECTRUMS CAN INCREASE POTENCY, ALONG WITH LONG WAVE uv LIGHT, SUCH AS uva OR SOME uvb.
Pardon cap lock!
I use CLW blurples known for increasing ganjas production of oil and terps compared to other lights and then CMH in there to fill in the blanks and get yields up to HID comparisons. The combo has worked tremendously well for me as teamwork makes the dream work ✌