as far i know, you are running dual stacked, but enabling this in advanced.
the only thing different is that there is one BGP session both for ipv4 and ipv6.
on my junos and cisco IOS i can't run 2 sessions to the same router with the same id eather...
I can't tell how to do that on IOS and Junos, but actually you CAN run ipv4 and ipv6 on the same machine at the same time.. i usually run on quagga, and it does run too..
there is a way to get this running.
make a new BGP instance.
and run your IPV6 session in that instance.
that should works, as we have this running for a another reason with our iBGP.
there are some other issues to take care of when making muliple BGP instances, but just try it.
Yes and no...i thought to run two bgp instances.. it's no problem, as the "propagation" problems within multiple instances can be safely ignored, as anyway ipv4 and ipv6 instances are independent from each other.
The problem comes when you have connect the router to a non mt router.
Since on quagga (but i think on cisco and juniper too), router id is single, the mt box refuses to establish the second session as remote router id is duplicated...