FortiWeb
A FortiWeb can be configured to join a Security Fabric through the root or downstream FortiGate.
Deepak_Girimaji_FTNT
Article Id 203372
Description

This article describes that the 'duplicate license has been detected' error occurs when a license (.lic) file that has been previously used is being re-used on a different VM instance. 

 

duplicate license.png

Scope FortiWeb.
Solution

To resolve this condition, the VM instance where the license was previously used needs to be shut down completely for at least 90 minutes.

After a 90-minute period the VM license de-registers from FortiGuard servers and it's possible to use it again on a new VM.

 

Note:

This is an automatic process and it is not possible to fasten it.