Multi-homed static mapping issue…

[Tantamount]

I've got a portable computer that has both ethernet and wifi interfaces.  Sometimes I use one, sometimes the other.  Of course, the hostname doesn't change just because I use one interface over the other.

I recently attempted to add a static mapping for the wifi interface of this computer, however it was rejected with this error:

The following input errors were detected:
This fully qualified hostname (Hostname + Domainname), IP, MAC address or Client identifier already exists.

I already have a static mapping for the ethernet interface, so I assume it's complaining about that mapping having the same hostname as the wifi one I'm trying to create.

With the dhcp servers I've used in the past, the entries really just care about the mac address to ip address association.  It's even allowed to have multiple mac addresses get the same ip.  As far as I know, hostnames aren't even part of this transaction.  It's when the dhcp client requests an ip that the hostname gets registered with dns, thus wiping out any stale records that might otherwise exist.

How are people handling this situation?  Is the hostname field really just a unique identifier for the dhcpd server (meaning I can really put anything I want in there), or does it use this information to add dns records too?