Feversaint

1 - Knock out a Casean (I used a gas grenade) 2 - Drag them from the ground onto your primary weapon slot in the inventory screen of a xenonaut soldier 3 - Hit escape to exit inventory screen 4 - Open inventory back up, a duplicated Casean will be on the ground. I've only tried this with Caseans on a single mission. I'm playing with Ironman mode so trying again and experimenting with different items would be a little time consuming and risky.