arp -a output
 

Separating from Variol's thread...

Here's the output from running arp -a on my system. For those unaware (like me!) ARP stands for Address Routing Protocol, and is a way for a computer to find other computers on the network. An ARP request is a broadcast request to find a particular computer (hey, who's VARIOLS_MACHINE). Every computer hears it, but only VARIOLS_MACHINE will respond. The asking computer will then keep a log of the computers it has talked with so that in case it wants to talk to one again, it can find it quickly. Entries in the log (aka the ARP table) will age out so it doesn't fill up forever.

For the record, I've got two NICs on my machine, wired and wireless. Arp -a gives me four NIC entries, two of which are my NICs.

Hmmmm.... and after investigating to post this, I discovered that the other two NICs are for the two VMWare installations I have on this machine. Why two? Well, one's an upgrade of the other... probably have to clean something up here ;) So no more mystery...

In any case, here's my output.

Re: arp -a output
 

VmWare was going to be my first guess. ;) It creates two virtual LANs.