local-mac works on every interface on sparc, the mac-address is usually build based on the hostid(M). if you set your local-mac-addresse? to true the nics will have its own MACs. but anyway "one nic is trying to assume the others IP" does not depend on the MACaddr. post the message and your ifconfig output, it seems that something else wants to get the same IP, or perhabs you have a bad IPMP configuration...

gP