Remote Desktop multi-user

I have setup a common-area computer (Until we get a VPN setup so users can go directly to their own desktop)for multiple users with remote desktop. This works fine, but it is going to be for 3-5 users, not concurrently, and the problem is if one user is connected and then a second user tries to connect, that will bump the first users connection. Is there any way to lock out additional connection attempts, so that if a second user tried to connect they might get a connection busy error or something similar.