Compiler Error CS0528

'interface' is already listed in interface list

An interface-inheritance list includes a duplicate. An interface can only be specified once in the inheritance list.

The following sample generates CS0528:

// CS0528.cs  
namespace x  
{  
   public interface a  
   {  
   }  
  
   public class b : a, a   // CS0528  
   {  
      public void Main()  
      {  
      }  
   }  
}