How to have two static addresses on one interface?

[Stephane Bortzmeyer <bortzmeyer@nic.fr>]

I want an IPv6 interface with two static addresses. If I write in
/etc/network/interfaces:

iface eth0 inet6 static
        address FEC0:1:0:FF00::1
        netmask 64
        address 2001:0910::1
        netmask 64

I get:

meowth:~ % sudo ifup eth0
/etc/network/interfaces:21: duplicate option
ifup: couldn't read interfaces file "/etc/network/interfaces"

So, I wrote:

iface eth0 inet6 static
        address FEC0:1:0:FF00::1
        netmask 64
        up ifconfig eth0 add 2001:0910::1/32

which does not seem very elegant: it hides the fact that none of the
two addresses is "primary".