I think if your TBH is long enough, it will take the bees long enough to really meet significantly. Since they are both small the fighting should be minimal since weak colonies and clusters tend to not fight anyway.
Bees know what resources they have to expend, small colonies don't have resources that large colonies do. It is why new installations and small colonies seem much more docile, and large booming colonies need to be treated with more respect.
If you two clusters/colonies are really small, there is also a really small chance of fighting.
Scot Mc Pherson<br />McPherson Family Honey Farms<br />Davenport, IA<br />BeeWiki: <a href=\"http://beewiki.linuxfromscratch.org\" target=\"_blank\">http://beewiki.linuxfromscratch.org</a> <br /><br />Pics:<br /> <a href=\"http://linuxfromscratch.org/~scot/pics/bees/\" target=\"_blank\">http://linuxfromscratch.org/~scot/pics/bees/</a>