I'm getting slave duplication when using the rules assistant to move the girls from the spa to the school. Here are some screenshots showing it.
It also happens without changing the outfit.
Steps to duplicate:
Start a new game
Make 3 spa tiles and add pools to them
Make 3 slave quarters tiles and add sleeping pods to them
Make 3 training room tiles and add school desks to them
Set a rule set as shown in the screenshot above (basically move from spa to school when obedience is max and fear is minimum)
hire 3 girls from Breeder's Show and assign them to the spa (you can hire them from anywhere, but Breeder's Show girls will already have max obedience and 0 fear so you won't have to wait for obedience and fear to reach their targets)
check the 'View Slaves' screen
wait a minute till they get transferred to the school
check the 'View Slaves' screen
Edit: The duplicate slaves no longer show in the 'View Slaves' screen if you save the game, quit to desktop, then run the game and load the save.
Edit2: All planets' prosperities are set to 0 (Abject Poverty) when loading a save.
Steps to duplicate:
Start a new game
Get enough money to make a Desk and a Combat Drone
Open the Galaxy Map and check some of the planets' prosperity.
Save the game
Exit the game
Start the game and load the saved game
Open the Galaxy Map and check some of the planets' prosperity. The all now have prosperity of 'Abject Poverty'.