Yes, it is possible to run two Ignition’s on the same machine. It just means they have to run on separate TCP ports. One will be 8088 and the other can be 8089. This file:
C:\Program Files\Inductive Automation\Ignition\data\gateway.xml
contains the two TCP ports (one for HTTP and one for HTTPS). You can download the Ignition Windows .zip install binary from our downloads page:
Unzip the file, change the ports in the xml file, and double click on the run-ignition.bat file to start it up. Don’t install a second Windows service though.
As far as the mobile goes, there is no advantage to using mobile over RDP. Both of them use resources on the server. So you can continue using RDP if that works for you. I guess the only advantage is being able to run on mobile devices without an RDP application.