Yes the physical port is shared - however there is a unique logical mgmt port per VDC. Which means you configure the mgmt0-interface on a per VDC basis with a spearate IP:
VDC1
int mgmt0
ip address 192.168.1.84/24
VDC2
int mgmt0
ip address 192.168.1.85/24
etc.
Regards
Marcel