Terminal Server.How to log in single user on all computer log in as a same user name without sign off

Hello,

I set up terminal server as a trial version.my all user log in perfectly but i have a little problem.

Problem is i want to single user log in all system.

Example:

computer1 login demo user in terminal server.when i connect computer2 in demo user so at a time computer 1 log off.i want to both computer log in as demo user.

Thanks.