How to go back two versions of Sunab PPA devel and how to Sandbox

Hi everybody,
I have been having some problems with audio on the last two releases
of the devel versions. The previous version overall was pretty good.

I was wondering how to go back to that. I can probably figure out how to get rid of the current version

sudo apt-get purge sunab:ppa-devel (or whatever the exact nomenclature is), but I am wondering how to get the version from two releases ago.
I only see the last to on the PPA page.

Also, does anyone have an exact idea how to run two version in Ubuntu 12.04 ? Let's say I wanted to run the fairly stable devel version from a few weeks ago and have a way to install / try the newest version without messing up the older one. Is this realistic on one log in ? Or should I make a new user / profile etc. Is it doable that way ?

Thanks,
Ross