Left center and right center speakers

I am running a 7.3.4 Dolby atmos system.  I have been doing research on dispersion of dedicated center speakers for home theater vs a book shelf or tower speaker to replace the center speaker.  This supposedly helps with dispersion for all seats in the theater.

I am currently doing some upgrades of the front and Surround speakers of the room.  I will have 2 left over bookshelf speakers.  I was going to use one bookshelf as the center and it will match the new incoming full range tower speakers.  Should I just use the one bookshelf in the middle or run a left center and right center speaker set up?  Part of the upgrade is a Trinnov Altitude 16 Processor.  I think it should be said if I am running a Trinnov seperate Amps are given.  So basically a 8.4.4