Refer to the diagnostic output:Two entries in the exhibit show that the same MAC address...

The MAC address "00:50:56:96:e3:fc" appearing in two different VLANs (4089 and 4094) in the diagnostic output indicates it is a MAC address associated with a device that supports traffic from multiple VLANs. Such a behavior is typical of network infrastructure devices like switches or routers, which are configured to allow traffic from various VLANsto pass through a single physical or logical interface. This is essential in network designs that utilize VLANs to segregate network traffic for different departments or use cases while using the same physical infrastructure.

References:

For more detailed information on MAC table diagnostics and VLAN configurations in FortiGate devices, refer to the official Fortinet documentation:Fortinet Product Documentation.