Multiple clown fish pairs?

[Nasabeau]

so, I am not adding more fish for at least another month or two due to an ich outbreak DX but I am still planning my tank, and figured this break can be a time to find information on doing something a little harder than normal. so, right now I have a YTBD, 2 Ocellaris clowns that are paired up, a tomini tang, a coral beauty angelfish, and a royal gramma. based on the name scheme my tank developed and the fish I like, I was going to finish out the tank with a solitary fish (maybe a wrasse or a chromis, I'm not really sure) and an additional pair of clownfish. I have a 75 gallon tank, does anyone have experience with multiple pairs of clownfish? are there any precautions to take? is it likely to work adding a new pair to a tank with an established pair? would a confirmed pair from the store be better than adding two unpaired or questionably paired fish? what if I bought a pair and QTd them together to get them bonded in the QT before adding them to the DT? I should add that I am really thinking about getting black occellaris clowns, is it better or worse that they'll be visually different?

 

[lapin]

My ipinion
Its a 50/50 chance the bonded pair you have now will kill the new 2.

 

[Nasabeau]

My ipinion
Its a 50/50 chance the bonded pair you have now will kill the new 2.

really? 50/50... dang... maybe not the best idea. does it help that the two I have now are young? (1.5 inches) maybe adding a larger pair would make that less likely?