When adding the Compliance Officer or Super Compliance Officer role to a specific user via API, the following error message may be displayed (Figure 1):
Figure 1 Error Message
This error means you are trying to add the Compliance Officer or Super Compliance Officer role when the user in question already has that role assigned to them.
If you would like to demote or promote the user, you need to first remove the role they currently have, then add the new role. Refer to the article here for more information on how to remove a role from a user.