Almost no one (aside from CatBrat) does what you are proposing, which, if I understand it correctly, is running two pairs of L/R fronts. There is no second center output on any receiver I know of, so if you're talking about running dual centers, your question is moot.

Seriously, dude, you've got the worst case of upgraditis I've ever seen.

I am the Doctor, and THIS... is my SPOON!