F.F.B. Plug-in

I'm playing the F.F.B. plug-in, and when I complete a mission for either the Rebels, of the Confeds about searching the Sepens Nebula for planets that are under control by the Red Aliens, the mission repeats itself. I accept the mission for the Confeds on Mars, and Palshife for the Rebels. Why does the same mission repeat?

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"Let it go. If it comes back, it was meant to be. If it doesn't, HUNT IT DOWN, AND KILL IT!!!"