Context is under-rated : what is this and why should we care ?
Thought the spoiler text explained it.
Basically, if you use Remote Desktop to log in to a Windows machine whilst another user is logged in, it will either kick them out, or, if both are Administrators, they can refuse the connection -- only one user is allowed in at a time.
Server editions of Windows have multiple logins enabled. There is a setting in termsrv.dll that controls this. So, you can either modify the .dll, or, better yet (this is Windows Update - proof) use a .dll wrapper to modify the parameters that termsrv.dll is loaded with.
Now, you can be using your computer, and your partner can log in to their account without kicking you off.
As mentioned, there is even a setting (if you wanted) to allow multiple instances of the
same account to be logged in at one time. I guess useful if you leave yourself logged in with a bunch of programs open, and want to remote in to do something without kicking yourself off?
See here for more details:
https://www.serverwatch.com/server-tutorials/remote-desktop-connections-for-multiple-users-on-windows-10-and-windows-server-2012.html
