Before the first war was declared by anyone, they had 2 planets.
In fact, the first war was declared against them. Their home planet was taken by the Yor, but it seems that they do not have the range to attack the second planet. I saw a fleet close by, but they just sat there for several turns then went back to their own territory.
Am I sure they colonized a second planet? Well, I did not see a colony ship. But in the first few weeks of the game I came across them, and they only had the one planet (of this, I am sure). Then sometime later I noticed that they had a second planet. The first planet had the larger icon of the home planet, and the second had the smaller icon. And when the original home planet was captured by the Yor, the capital reverted to the second planet.
I have seen, in many games, minor races with more than one planet. I have seen them send troop ships to invade other planets, and capture them. It does not happen very often, but it does happen.
I just wish I knew how to make them do it more - to be more aggressive.
In the earliest versions of DL it happened a lot more. A minor would show up and all but take over the galaxy. It frustrated the he!! out of me, at the time.
Too bad that those kinds of things were so severely edited out. They made for some very interesting game play. But instead of simply reducing the effect, the devs decided to get rid of them altogether.