preupgrade F16 > F17: duplicate dhcp entry?

[sean darcy]

I've got a running F16. The DHCP server gives it an address of 
10.10.10.100 based on the MAC address. I'm trying to use preupgrade-cli 
to upgrade to F17.

Preupgrade-cli works fine on F16. Then when I reboot into the upgrade, 
it fails saying it finds a duplicate entry for the dhcp address of 
10.10.10.100.

Same MAC. What's the problem?

sean