There is a section in the Foundation Training course that describes the different run modes to you. There are three run modes available, Exclusive (the default), Foreground, and Background.
You can only run multiple sessions on the one machine if none of your objects are set to exclusive mode, and if no more than one of your sessions is running a Foreground object, all other objects must be set to background mode.
To be able to set an object to background mode two things must be true. Firstly, you must have no Surface Automation, Global clicks, or Global send keys anywhere in your object. If you do than the object requires forground focus and should be set to Foreground mode. Secondly, it must be an application that allows multiple sessions on the same desktop - some applications do not allow this (i.e. some mainframes only allow one connection, some windows app do not work if you try to run it twice, etc).
If you have no global interactions and the applications you are use allow multiple use on the same desktop (and allow multiple interfaces to it at the same time) - then you could run multiple resourcepcs on the desktop using different ports and have sessions running in each. It is likely there will be a performance impact on each session you add as they each use the resources allocated to the desktop.
It must be noted that the saving from be on being able to run multiple sessions on the same desktop is a saving in infrastructure only (less virtual desktops required) the number of Blue Prism licenses required would be the same. So 4 concurrent sessions on one desktop would still require 4 Blue Prism licenses, irrelevant of them running on 4 separate desktops or all on the same desktop.
From my experience I is extreamly rare no objects in an environment to have global interactions, so it is very unusally for multiple sessions to be running on the same virtual desktop. The most likely solution to your problem would be the need to provision a 2nd resource to run your task.
