Overdriving fluorecents...

I had read about overdriving flourescents and basically what that means is connecting a 2 light fixture into a 1 light fixture so that it has twice the power and light output.

I was thinking about adding two 4 foot fluorecent lights to my one 400 watt mh and was going to overdrive both to achieve a good source of supplemental light.

What are your thoughts about this idea??has anyone ever grown with fluorecents combined with mh or hps before??