[CentOS] Second Xen NIC not being recognized?

>Both NICs show up in the Xen hardware details display.
>Looking at dmesg output from rebooting the domU, I see both eth0 and eth1
>appearing there.

By chance did you set the macs manually? Are they valid, look for a typo?
I recall hearing about this behavior in lieu of that mistake.

jlc