We prefer two center speakers. Ideally one above and one below the screen. Second best it to have one close to the screen and one closer to the listener. Last would be what you describe.
Ideally we would have the ability to attenuate the volume of the two centers when they are in first two scenarios mentioned above. In your situation they would be at equal volume level.
Your only concern would be in the amplifier can drive two centers. Assume a standard AVR with 8ohm speakers... You shouldn't have any issues.
I'm Not an engineer, but I play one on TV. My handle is Tweety but I have nothing to do with the organization of similar name. I just had a really big head as a child so folks called me tweety bird.
