No. Only one running instance of OpenSpan.Runtime.exe can be running on a machine. Only one solution can be running at a time. If you want multiple solutions running on the same machine, the suggestion is to merge the projects from the solutions into one solution.
Question - is it possible to have 2 different versions of Runtime installed given that each Automation my be associated with different Runtime versions...? Yes, I understand that only 1 instance can be running at a time, while I do not require multiple automations to be running at the same time, I would require that different versions of the Runtime be available on the machine as each Automation may require a different Runtime, is this possible via Command Line and File Share distribution..?