From Carl's Guide:
Cloning Machine
(Level 5, 2 Common Metals, 2 Common Crystals)
Can be upgraded at level 8. The cloning machine requires you to place an object upon it. When a valid item, such as a collectible is placed, that object can be cloned. This can be very handy to making serums, as well as any other item in the game that you need more than one to make something. You can save a lot of money on food with this, as meals can be cloned, as well! To clone an object multiple times, just take the new one off and clone the original again. When upgraded, it will let you clone a Sim! The new Sim will join your household and have the same traits and appearance as the original, though there is a chance they get some evil clone traits, like mean or evil. They will not, however, have any of the Skills of the original, nor a Career.
https://www.carls-sims-4-guide.com/careers/gettowork/scientist/
I've never used it to clone a sim. Maybe it's time.