Which Watts Retro kits should I get? (96w vs 2x96w)

Hello all,
I have kept just about any fish in my life, but I've NEVER done plant tank before. I must say that now I am completely hooked and just bought a 46gallon euro tank with a stand today mainly for a plant tank.

Now after some research, I am aware that you want 2wpg or more, but I am kind of curious/confused in the situation I am in.

2x45=90wpg , so I was thinking if I can just get 1x96watt retrofit from http://www.ahsupply.com, or go a little overboard and get 2x96watt retrofit?

My main question would be, would the plants grow the same with 1x96w or 2x96w? I searched and some people said 2wpg light with good co2 will grow plants better than more than 2wpg light with co2. When I read that I was confused like a drunken dog lol because In my head, the more light the better for the plants?

I am planning to run a pressurized co2 kit as well since i heard in order for your plants to not only survive, but grow you need the co2.

My goal is to do everything right the first time hence I want to ask before I make a decision on the lights.

TIA!
JP