Restrict user to only 2 sessions

I need to limit the number of sessions a USER can have on our rdp server.

I have the option to allow :

I found this setting to allow multiple connections:

http://technet.microsoft.com/en-us/library/cc753380.aspx

but I wasn't sure that is what I need. It says:

You can configure the number of simultaneous remote connections that
are allowed for a connection. Restricting the number of simultaneous
remote connections can improve performance of the computer because
fewer sessions are demanding system resources.

Which, to me, seems like an overall connection limit and not a user limit.

Is this the right setting? If not, what is the setting to only allow them 2 sessions per user?

If possible, I'd like this to be a GPO setting. I'm not sure if that is possible though.

Thanks!

UPDATE#1

A little background to my issues:

We have 3 virtual servers:

1. Domain Controller – Windows 2008R2 x64
2. SQL Server server – Windows
3. 2008R2 x64 RDP server – Windows 2008 x32

The RDP server needs to run on a 32 bit operating system due to a legacy program that will not run on a 64 bit machine. (don't ask)

The RDP server has this application running through a terminal services published application.

All is working well but our customers are connecting 3 to 4 times and we want to prevent that. We don't want to overload the server. Besides, we told them they could use two sessions (application instances) per user.

I'm hoping there is a setting that we can say, 2 sessions per user so we don't have to make any programming changes.