using the same agent for different build simultaneously

Hi, this is my question:
 

How to use the same agent for several builds simultaneously?

I have a Windows agent with several CPUs , I would like to use it for different builds at the same time. But the problem is that when one build is running on that agent, the other build waits for the first one to finish.

How to force the second build to use the same agent at the same time and not to wait?
 

Thanks