I have 2 on-board g-ethernet ports.
I configured
eth0 - 10.1.1.2
eth1 - 10.1.1.3

I connected ethernet wire to eth0 from XP machine which 10.1.1.10.
And then I setup "tcpdump -nt arp" at the linux machine to watch ARP.

At XP machine, I typed "ping 10.1.1.2", and I got mac addr of eth0.
So far so good.
But when I typed "ping 10.1.1.3", then eth0 replied to ARP and sends mac of eth0.

At XP machine, I typed "arp -a", and see

10.1.1.2 Mac of eth0
10.1.1.3 Mac of eth0

Remember nothing is plugged in eth1!!
Anyone knows why eth0 responds to the ARP request for 10.1.1.3????