Windows 10: Multiple RDP Sessions

To have concurrent user sessions working in Windows 10, you need to make small changes to termsrv.dll file. This file is located in C:\Windows\System32 folder. Before modifying termsrv.dllfor the first time, you need to take ownership and assign yourself full permissions. You also need to stop Remote Desktop service (TermService) if it’s running.

https://www.mysysadmintips.com/windows/clients/545-multiple-rdp-remote-desktop-sessions-in-windows-10