Multiple VIPs not possible with NLB in multicast mode?

Dear all,

I've been researching the matter for quite a while by now and I just
get a stronger idea that multiple virtual IPs cannot really be used in
an NLB cluster running in multicast mode.

I've added an extra IP to the cluster configuration, the cluster
converged successfully and is accessible from a neighbouring server on
the same subnet, but not from other subnets. Two static ARP entries
have been created on the routers, one for the cluster's primary address
(which appears in nlbmgr GUI and the registry) and one for the
secondary address (as appears as a result of 'wlbs ip2mac' for the
given address, but I guess they both are just hashes of the IPs,

The primary address works fine, but the secondary one doesn't. Viewing
the ARP cache on the neighboring server reveals that both addresses use
the same MAC! The networking people tell me the routers will not accept
two static arp entries with the same MAC, and I have no reason not to
believe them. What do I do then?!!! Is it virtually an IMPOSSIBLE

Any help will be greatly appreciated,