Sunblade shows 2 MAC address on same port

Please, can someone tell me why my SunBlade would be showing 2 different but similar MAC addresses on the same port on the Switch? The switch shows all other Workstations with 1 MAC on each port, but the SunBlade is showing 2. Thanks in advance for any insight....

Is there a virtual interface configured with the second MAC assigned? (Check with ifconfig -a as root).