Remove duplicate filtering in UsingCodeFixProvider

Fixes #2000

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/OrderingRules/UsingCodeFixProvider.cs

@@ -710,20 +710,7 @@ private List<UsingDirectiveSyntax> GenerateUsings(List<UsingDirectiveSyntax> usi
                         processedUsing = processedUsing.WithAdditionalAnnotations(FileHeaderStrippedAnnotation);
                     }
 
-                    // filter duplicate using declarations, preferring to keep the one with an alias
-                    var existingUsing = result.Find(u => string.Equals(u.Name.ToNormalizedString(), processedUsing.Name.ToNormalizedString(), StringComparison.Ordinal));
-                    if (existingUsing != null)
-                    {
-                        if (!existingUsing.HasNamespaceAliasQualifier() && processedUsing.HasNamespaceAliasQualifier())
-                        {
-                            result.Remove(existingUsing);
-                            result.Add(processedUsing);
-                        }
-                    }
-                    else
-                    {
-                        result.Add(processedUsing);
-                    }
+                    result.Add(processedUsing);
                 }
 
                 result.Sort(this.CompareUsings);

StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210CombinedSystemDirectivesUnitTests.cs

@@ -138,6 +138,7 @@ namespace Food
 {
     using Food;
     using global::Food;
+    using global::Food;
     using global::System;
     using global::System.IO;
     using global::System.Linq;

StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210UnitTests.cs

@@ -198,6 +198,7 @@ namespace Foo
     using corlib::System;
     using Foo;
     using global::Foo;
+    using global::Foo;
     using global::System;
     using global::System.IO;
     using global::System.Linq;