In the current build (0.1.7), a sector can't have two of the same job, so there's no way that bug can happen. If you are playing the current build, you're probably playing a save game from a previous build, because the sector jobs are all generated and saved when you start a new game, so an old save will still have jobs that a previous build generated.
Start a new game in 0.1.7 and you shouldn't have this problem. Sorry about constantly having to start anew but that's alpha testing for you.