Ativar várias sessões RDP
Log into the server using Remote Desktop.
Open the start screen (press the Windows key) and type gpedit.msc and open it
Go to Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Connections.
Set Restrict Remote Desktop Services user to a single Remote Desktop Services session to Disabled.
Double click Limit number of connections and set the RD Maximum Connections allowed to 999999.
Mas temo que todo o seu aplicativo seja compatível com várias sessões. Terminal server ou VDI é uma solução completa que precisa ter um custo adicional.