Do not create a new native pointer property if the base class already provides one.

src/Generator/Generators/CLI/CLIHeadersTemplate.cs

@@ -197,12 +197,25 @@ namespace Cxxi.Generators.CLI
             var nativeType = string.Format("::{0}*", @class.QualifiedOriginalName);
 
             if (@class.IsRefType)
+            {
+                Class baseClass = null;
+
+                if (@class.HasBaseClass)
+                    baseClass = @class.Bases[0].Class;
+
+                var hasRefBase = baseClass != null && baseClass.IsRefType
+                    && !baseClass.Ignore;
+
+                var hasIgnoredBase = baseClass != null && baseClass.Ignore;
+
+                if (!@class.HasBase || !hasRefBase || hasIgnoredBase)
                 {
                     PushIndent();
                     WriteLine("property {0} NativePtr;", nativeType);
                     PopIndent();
                     NewLine();
                 }
+            }
 
             GenerateClassConstructors(@class, nativeType);