Yes, adding a second 1G switch will give an additional 10 external ports. The switch itself will be connected to the second of two ports on the on-Blade two-port 1G Ethernet NIC (chip). This second switch can be either redundant or load-sharing; you define this in the configuration of the on-board NIC in the OS using either “Teaming” for Windows or “Channel Bonding” for Linux. There is a feature in the switch called ULFT which must also be configured to match whatever attributes you define in the NIC configuration. Details are in the Supermicro SuperBlade™ Blade Network Modules User’s Manual section 6-14.

Please also understand that it is not necessary to do this in order to have multiple VLANs per Blade. Please see sections 6-3 and 6-4 for more about how VLANs work in this switch and how they are configured.