Do Commercial Theaters Use Multi Center Channels?

Yes. They are pro speakers like used at concerts. Multi driver arrays that are bi or tri amped. See link to a jbl cinema speaker designed to be behind a screen.

http://www.jblpro.com/catalog/general/Product.aspx?PId=324&MId=1

The two theater installations I've had the oppertunity to check out behind the screen, many years ago via friends, were THX certified JBL installations that had three identical full-range speakers (L/C/R) across the stage using some of these, and these.

More vintage JBL pro stuff here.

And pro THX Info here

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