The Duplicate Serial Number error displays in the Management Console.
The virtual appliance serial number is a unique identifier that can be used in only one instance of a Management Center Virtual Appliance (MC-VA). You are receiving this error because Blue Coat detects more than one MC-VA sharing the same serial number.
From the licensing/entitlement investigation, it would be found that backend pings have been received from public IPs x.x.x.x and y.y.y.y, and in the last two (2) hours, we have had pings from x.x.x.x only, looking like the other appliance with the y.y.y.y public IP address may have been shut down. Clearly, this validates the fact that the serial number would have actually been duplicated in two different instances, hence, the reason for the "License suspension by duplicate serial" that was received.
Please note that this isn't a bug but an actual case of asset duplication.
This issue automatically resolves itself within an hour of MC-VA runtime. If you issued the CLI command multiple times shortly before the Duplicate Serial Number error occurred, wait an hour for the error to clear.
You issued the restore-defaults factory-defaults command in the command line interface (CLI) multiple times in a short period of time, which caused the MC-VA to identify itself incorrectly as a duplicate.
The presence of a warning beside License Validation Status on the Health Monitoring tab (Maintenance > Health Monitoring) may also indicate that the MC-VA identifies itself as a duplicate.
If the restore-defaults factory-defaults command was not issued and there is no warning in Health Monitoring, proceed to Cause 2.
Multiple MC VAs in the network are using identical appliance serial numbers, and the license has been suspended.
This is also a bug in Management Center v3.1, fixed in 3.2: https://knowledge.broadcom.com/external/article/210376/management-center-gui-indicate-license-s.html
Complete the following steps: