I've just encountered this little one for the second time.
Sometimes a race (in my case it was the Acutians both times) will decide to build TWO outposts simultaneously.
In this case it was a Manufacturing outpost and a Science outpost (both times).
The Outpost Building Fleets will both fly to the exact same spot, one of them will build their outpost (manufacturing one time, forgot which one the other time), and the other fleet will just kinda sit there looking at it like someone just took their parking spot.
I'm reporting this as I'm looking at the second one so I'm not sure what it'll do from here, but the first time the Outpost Building Fleet eventually flew off to heroically conquer the Peltian homeworld.
Hilarious to watch, but probably not the intended behaviour.
