'arg' duplicate named attribute argument
A parameter, arg, on a user-defined attribute was specified twice.
The following sample generates CS0643:
using System; using System.Interop; [attributeusage(AttributeTargets.Class)] public class MyAttribute : Attribute { public MyAttribute() { } public int x; } [MyAttribute(x = 5, x = 6)] // CS0643, error setting x twice // try the following line instead // [MyAttribute(x = 5)] class MyClass { } public class MainClass { public static void Main () { } }