Remove also duplicate imports.

pkg/analysis_server/lib/src/services/correction/organize_directives.dart

Index: pkg/analysis_server/lib/src/services/correction/organize_directives.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/organize_directives.dart b/pkg/analysis_server/lib/src/services/correction/organize_directives.dart
index b12ecb138b6dcebba5b05aa8874da0709bc69883..c7ea89ec154abb117601fd5a9e63ed5d2b4851dd 100644
--- a/pkg/analysis_server/lib/src/services/correction/organize_directives.dart
+++ b/pkg/analysis_server/lib/src/services/correction/organize_directives.dart
@@ -9,7 +9,6 @@ import 'package:analysis_server/src/services/correction/strings.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/scanner.dart';
-import 'dart:math';
 
 /**
  * Organizer of directives in the [unit].
@@ -57,7 +56,8 @@ class DirectiveOrganizer {
 
   bool _isUnusedImport(UriBasedDirective directive) {
     for (AnalysisError error in errors) {
-      if (error.errorCode == HintCode.UNUSED_IMPORT &&
+      if ((error.errorCode == HintCode.DUPLICATE_IMPORT ||
+              error.errorCode == HintCode.UNUSED_IMPORT) &&
           directive.uri.offset == error.offset) {
         return true;
       }