2 Center channels

Has ayone experimented with using 2 center channels in their HT setup? If so, how did you place the speakers and what were the plus and minus of such a setup?
Thanks for your comments.
My center channels are doubled speakers; so are my mains. I took PSB Alpha A/V's, unscrewed the backs of the speakers, drilled holes into the bottom of the cabinets and bolted each pair together so that the woofers are joined at the together and the tweeters are on the outside. My mains (front left and right) are exactly the same.

How does it sound? MUCH better than with just a single speaker. It has a lot more "fullness" to the sound. Since my speakers are bolted together at the bottom, I've turned some bookshelf speakers into really tall bookshelf speakers that I simply turned on its side and placed under the TV.

I hope this helps!
Any time you use two speakers close together, you're going to get some unpredicatble phase cancellation - good center channel designs seek to minimize the problems of multiple drivers and provide good horizontal dispersion. Why would you want to go that route? Unless you have two speakers you're aching to use, you'd be better off to buy one good speaker.