Adding another light into the grow tent

Hi
I currently Have 2 Marshydro MarsII 400w LED lights in a 1.4x1.4x2 grow tent.
I want to add another light & was looking at getting the more powerful 700w MarsII LED but was wandering if that would not be a good idea & I should get another 400w MarsII LED so that the light is even and no bright spot or even the plants under the 400w bend towards the 700w.I would like some advice please I haven't had the 400w lights long and am very happy with my results. It just the coverage I struggling to fit 6 plants under 2 lights.
Thanks
Weed22

kinda late on it but im planning on running 2 700w in bloom and i have just the one for veg right now but i figured id do about the same amount of plants u r in a scrog and just fill in the gap's with 300w's or 600's old model 3w diode less penetration means i can put them closer than the mars ii 5w. completly filling the gap and still not burning em. i mean im gonna do it. not done yet but the 1 700w raises temps by 10-15 degrees farenhiet

I bought the new 5w mars reflector and it didn't take me long to figure out they were overpriced inefficienct and loud.
I went the diy route and couldn't be happier, I have 4 cxb3590 for roughly the same price as my Mars and the difference in heat/power output is insane.
Long story short yes you can add more Mars to your space but you will need to improve your ventilation to keep temps down.

If you add a second fixture to a tent do you raise the height of both fixtures or run at recommend height?

Math out the square footage. Generally you don't need more than 40 watts per sqft, 30 - 35 with high quality LED.