An extension of name clientcredentials already appears in extension collection, extension name must be unique.

When we browse the web page it loads fine and continues working. Once we close the IIS manager and open it again, the following section gets added to the web.config file automatically :   <extensions>    <behaviorExtensions>     <add name=”clientCredentials” type=”System.ServiceModel.Configuration.ClientCredentialsElement, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089″ />     <add name=”serviceCredentials” type=”System.ServiceModel.Configuration.ServiceCredentialsElement, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089″ />…