Ilios allows Learner Groups to be copied either with or without the learners. This will be shown in greater detail soon in this location. It is a very handy recent functional addition to Ilios.
To copy a Learner Group, the "Copy" icon (the same icon is also used in Copy Session) is used to start the process. The arrow in the screen shot below shows this icon within Learner Groups.
Once the Copy button has been pressed (as shown above), you can either create a copy of an existing group (and any sub groups) with the same Learner membership as the one you are copying or empty to be populated later.