Without more detail it's hard to say with any accuracy what the result will be, but here are a couple points.

You will add more lumens to the room. Light = Yeild
Many growers sub out a small number of HPS for some MH lamps in their room to add blue light.
As long as heat is not an issue, I don't believe it can hurt.
SoCoMMJ Reviewed by SoCoMMJ on . question on grow lights we are running a HPS 1000 lite and was wondering if we add a 1000 non-sodium lite to the mix will it effect the grow.?? Rating: 5