In Dynamics 365 Customer Engagement(8.2), if you change a Business Unit’s parent BU, custom security roles in the Business Unit may be duplicated.
If you then change the parent BU a second time, a third copy of the roles will be created. This is a known issue. If it happens to you, open a ticket with Microsoft support, or alternatively, recreate your custom security roles.
Thanks to Eric Labashosky for bringing this to our attention.