Delete the SNMP profiles with the duplicate user name so that there is only one profile with that username.
1. If you have just NFA go to Admin->SNMP Profiles and delete the profile from there.
2. If you have CAPC, go to Admin->Configuration Settings->SNMP Profiles and delete the profiles from there.
3. After deleting the profile force a Full Resync of the NFA Data Source from the Admin->Data Sources page of CAPC and allow some time for it it complete.
4. You can verify that the profile has been deleted by checking the snmpprofiles table on the Harvester servers databases.
In 9.3.3 and earlier use:
mysql poller
select * from snmpprofiles;
In 9.3.6 and later use:
mysql harvester
select * from snmpprofiles;
5. Once you verify the SNMP profiles have been removed from NFA, try to Rediscover and Refresh the devices again from the Admin->Enable Interfaces page of NFA.