create new proxy for same wcf service without clientcredential

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WCF

I have created proxy like:

ServiceReference1.Service1Client proxy = new ServiceReference1.Service1Client();
           proxy.ClientCredentials.UserName.UserName = "Second";
           proxy.ClientCredentials.UserName.Password = "Second";
proxy.GetData();

When I am creating New object for same service, Again its asking for authentication

<pre lang="cs">ServiceReference1.Service1Client proxy2 = new ServiceReference1.Service1Client();
proxy.GetData();</pre>

client should authenticated only once.
I am using below security and session contextmode:

Security:

<security mode="TransportWithMessageCredential">
                       <transport clientCredentialType="None" />
                       <message clientCredentialType="UserName" />
                   </security>

Session:
Persession


Can't we create access methods with new object without giving credentials again.