An example of where I used this: There is a third party application running at a client site and it doesn't seem to work for any other user except for the administrator account on that machine. The client wants to get in there and start using the program but the vendor is unavailable to assist at the moment. By allowing multiple people to log into the single administrator account, it helps progress move forward. THIS IS NOT IDEAL FOR A LIVE ENVIRONMENT.
A note to people making config changes: PLEASE TEST YOUR CHANGES. DO NOT ASSUME THIS WILL JUST WORK SINCE I SAID SO. This is a VERY important step and seperates the posers experts and the real experts that know better.
The following is for Remote Desktop Services (RDS). Microsoft (MS) rebranded Terminal Services (TS) as RDS. This process can be done with any user that has privileges to do this and it affects all users logging into that server.
Step 1 - Navigate to 'Remote Desktop Session Host Configuration'
To get here, go to: Start -> Administrative Tools -> Remote Desktop Services -> 'Remote Desktop Session Host Configuration' (See Figure 1 below)
Step 2 - Uncheck the 'Restrict each user to a single session' box.
Once in Remote Desktop Session Host Configuration, under the 'Edit Settings' section, look at the options in the General option. The third one down should read 'Yes' if you log into the server and immediately take over an active session. Double click on this option and you will see the form in Figure 2 pop up. Uncheck the 'Restrict each user to a single session' box and click Apply.
Step 3 - Validate the changed setting
While keeping your current session open, open a new RDP session and log in as your current user. If the new window opens a fresh instance on the server, you're all set!
Hope this helps!