I got a divider from petsmart the other day when I got my crowntail male. I put him in with Autumn's and the divider in her 6 gallon tank and coming back later I found her on his side. They weren't fighting but she was trying to be the dominant one and was staring him down. It scared me though cause I thought they had hurt eachother. I had to leave them in there a couple days since his tank wasn't fixed up, so I put a sponge in the spaces she could possibly squeeze through and pushed the gravel rocks up more around the divider. It worked, but they still could almost touch noses on one side....I had to cut it down to size so I can't take it back, but I might just use it for a moss wall. If I figure out a way to make it safer, I might use it again, idk....haha o_o;
That's good your betta's are safe even though that happened. :)
"Life is an adventure full of beautiful things, and a treasure worth more than gold."