WCF Web Service with several clients

Question

Hello everyone.
I'm trying to create  WCF Service App (that is hosted on IIS under Win XP Pro) with wsDualHttpBinding support. The idea is quite simple - create smth like chat server but host it withing IIS.
I've got such a problem: in client's app.config I manually set clientBaseAddress="http://localhost:8000/client"
and when I try to launch 2 client console app's I get next exception:
HTTP could not register URL http://+:8000/client/. Another application has already registered this URL with HTTP.SYS.
Is there possibility to enable port sharing for HTTP, or only TCP available?
If no - if it's possible to launch console app from web service?