FortiWeb
A FortiWeb can be configured to join a Security Fabric through the root or downstream FortiGate.
Deepak_Girimaji_FTNT
Description This article discusses about activating license using the same license(.lic) file which was used previously would result in error 'Duplicate license has been detected'.
Scope  
Solution

Wait for 90 minutes for the license to update.

This may also take upto 24 hours for the systems to be updated.