I was playing the beta version last night when I had two colony ships hit an uninhabited planet on the same turn.
It let both colonize it (i accidentally said 'yes' to both prompts to colonize). This led to the planet having issues several turns later. chief among them was that a few turn later everything in its build window stated it was going to take thousands of turns to complete.
I really like most aspects of the beta (0.41) so far.