The randr-1.2 git branch is no longer used, it has been merged into master. If you want to test your luck with Randr 1.2 functionality, install the driver as usual, using at least xorg-server version 1.3. Add the line
{{{
Option "Randr12" "true"
}}}
into your xorg.conf in the {{{Section "Device"}}} that calls the Nouveau driver. Do realize that dual head support is in its infancy and probably cannot drive your monitors correctly. See the FeatureMatrix about supported cards.
== Current known issues ==
HW cursor has issues on analog VGA if on second RAMDAC on single head
