If you tried to develop a simple WCF function, and you tried to write in your WCF 2 overloading functions in WCF, you will not be able to deploy your serivce and the clients will get an exceptions.
The solution: give Aliases to the overloaded functions in the WCF service.
public interface IMyWCFSvc
string GetCustomerInfo( int CustId);
string GetCustomerInfo( string CustomerEmail);
The proxy when you reference to your serivce, will create 2 methods with the Alias names and not with the actual overloaded name in C# code.
Hope this helps.