Comment 14 for bug 176125

The way I got it to right (didn't reboot since some time so I'm not sure it's still ok):

net.ipv6.conf.wlan0.use_tempaddr = 2
net.ipv6.conf.eth0.use_tempaddr = 2
net.ipv6.conf.all.use_tempaddr = 2
net.ipv6.conf.default.use_tempaddr = 2

in /etc/sysctl.conf

and ipv6

in /etc/modules

After that, I get two dynamic addresses in ip addr, the secondary is the random one.