[Ripley]

Just with my experience (and my two bettas). They were in a ten gallon, side by side, with a clear divider between them. And not once did I see them flaring at each other or trying to get at each other. They both seemed quite content - maybe even happy to have some company. They could've jumped over the divider, but didn't (I guess neither of them are real jumpers). So, I don't see a problem with your set up. Maybe you could try to find a real tank divider and put on on each end of your tank? That might give them a bit more room. Just an idea!