Hi,

For multiple endpoints for the same service, you need to specify endpoint name for each endpoint, and then when you create client, you need to pass the endpoint name in the constructor. then you can create your client as follows:

using(CalculatorClient client = new CalculatorClient ("endpointConfigurationName"))
{

}

 Please check this article: http://msdn.microsoft.com/en-us/library/ms733133.aspx

Regards,
Peter