If you use DevStack you can't! While running stack.sh an error occurs because you can't enable both version. I don't know if it's a misconfiguration or a bug, anyway if someone knows how to do this it would be really helpful!

You should be able to have both. There is only one restriction. The two agents can not be active on the same node at the same time. You need two separate network nodes, one for v1 and another for v2. Since DevStack runs everything on one single node, you can never have both there.