Two planet owners... or how I lost a planet to the Drengin

I had an odd occurance happen in my last game. I had just colonized a planet that the Drengin were headed towards. After setting the original production, I ignored the planet for a little bit. A turn or two later, I noticed that the planet had become a Drengin planet, however it still showed up in my list of planets for a few more turns. I could edit what was being produced through the colony list, however that had no berring on what actually came out of the Drengin controlled colony.

At the time this happened, there was no war (the Drengin had not yet researched enough to build transports).