Multiple clients on terminal server not working.

The best is to contact local support

Please see  Tech Note "tn000031136" / "Remote Desktop Services with Vijeo Citect 2015" for details on how to setup multiple clients in this terminal server environment.

It looks all users shared the same session of the runtime manager. All you need to do is let each user launch citect32.exe with a parameter /x. In this way, each user will have her or his own session of citect runtime. Hope this would help.

Hi Jacky Lang , is this documented somewhere? 

Yes Richard. It is documented in Tech Note as mentioned byOlivier in his reply. I just provided a short answer.

As for license, the /x client always look for a floating license in SCADA network. To force it to consume the local USB licenses, you need to add parameter [Client]UseLocalLicense = 1 in Citect.ini on the terminal server. Unfortunately, this parameter is missed in Help. But you can search for UseLocalLicense in https://softwaresupportsp.aveva.com/#/technotes where there are a few Tech Notes for how to use this parameter.