VPN with two mac users
I have a very dirty work around. So I hope someone will come up with a better solution.

What I did is setup a Virtual Box virtual machine with some minimalistic Linux that can do VPN. Once the virtual machine is connected the user can use the VPN inside the machine (but other users not). Since I needed to use some apps in the host system I finally set up a proxy in the virtual machine that would forward my VPN users data.

As I said dirty...