We got this error while trying to import managed solution to our TEST environment.
The detail of the error message clearly tells the reason for the error.
The error was because that we had a similar a role with same name in our TEST environment, and in DEV we had renamed that existing role and had created a new role with similar name.
So, while trying to import the solution, CRM was getting confused as it was able to find the role with same name but different id.
To fix this either rename the Role in DEV and export and import it back or rename the role in TEST to and them import the same solution.
Hope it helps..