Run different Gramps versions parallel

From Gramps
Fig. 1 Running Gramps 3.00-1 and 3.1.0-0.SVN10653...- in Virtualbox
Fig. 2 Running Gramps 3.00 in a Fedora Virtualbox on Ubuntu.
How to run two versions of Gramps together on one machine?
Use virtualization software like Virtualbox.
Why
One of the side effects of converting Gramps to be a more modern Gtk application was making it a 'Gtk Application". The Gnome folks designed that so that only a single instance can be run at one time.

See also