useradd

Create a new user, with a home

-g Primary group of users
-m Create the user's home directory
-N Do not create a group with the same name as the user
-s login shell of the new account

useradd -g users -m -N -s /bin/bash <user>

Create a new cloned user

useradd -g primary-group -o -u `id -u primary-user` username