Racoon doesn't check for the case when there are
multiple network interfaces with the same IP address
on a host and tries to bind to the address as many
times as there are the interfaces with that address.
Obviously only the first attempt may succeed, the
others are reported as "failed to bind" errors.
This patch makes racoon to disregard multiple
occurences of an IP address and in consequence to try
to bind to every single IP address only once and thus
to avoid unnecessary "failed to bind" errors.