MH & HPS growing

Has anyone ever tried, or seen people grow with Metal halide, and HPS lights side by side before?

Either during vegging or flowering?

I'm currently vegging and I was thinking about buying a HPS lamp to throw along side my MH lamp, I mean it couldn't hurt really could it?

i am curently using HPS 600w with a 600w digital ballast....i just started my grow but all i'v read has giving nothing but good marks for HPS.....thats should be a good combination for you if you grow right