diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index ac59ae8..83a28bc 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -503,6 +503,7 @@ module ApplicationHelper
     text = Redmine::WikiFormatting.to_html(Setting.text_formatting, text, :object => obj, :attribute => attr)
 
     @parsed_headings = []
+    @heading_anchors = {}
     @current_section = 0 if options[:edit_section_links]
 
     parse_sections(text, project, obj, attr, only_path, options)
@@ -816,6 +817,11 @@ module ApplicationHelper
       anchor = sanitize_anchor_name(item)
       # used for single-file wiki export
       anchor = "#{obj.page.title}_#{anchor}" if options[:wiki_links] == :anchor && (obj.is_a?(WikiContent) || obj.is_a?(WikiContent::Version))
+      @heading_anchors[anchor] ||= 0
+      idx = (@heading_anchors[anchor] += 1)
+      if idx > 1
+        anchor = "#{anchor}-#{idx}"
+      end
       @parsed_headings << [level, anchor, item]
       "<a name=\"#{anchor}\"></a>\n<h#{level} #{attrs}>#{content}<a href=\"##{anchor}\" class=\"wiki-anchor\">&para;</a></h#{level}>"
     end
diff --git a/test/unit/helpers/application_helper_test.rb b/test/unit/helpers/application_helper_test.rb
index a8652b3..7024f6f 100644
--- a/test/unit/helpers/application_helper_test.rb
+++ b/test/unit/helpers/application_helper_test.rb
@@ -837,6 +837,33 @@ RAW
     assert textilizable(raw).gsub("\n", "").include?(expected)
   end
 
+  def test_table_of_content_should_generate_unique_anchors
+    raw = <<-RAW
+{{toc}}
+
+h1. Title
+
+h2. Subtitle
+
+h2. Subtitle
+RAW
+
+    expected =  '<ul class="toc">' +
+                  '<li><a href="#Title">Title</a>' +
+                    '<ul>' +
+                      '<li><a href="#Subtitle">Subtitle</a></li>' +
+                      '<li><a href="#Subtitle-2">Subtitle</a></li>'
+                    '</ul>'
+                  '</li>' +
+               '</ul>'
+
+    @project = Project.find(1)
+    result = textilizable(raw).gsub("\n", "")
+    assert_include expected, result
+    assert_include '<a name="Subtitle">', result
+    assert_include '<a name="Subtitle-2">', result
+  end
+
   def test_table_of_content_should_contain_included_page_headings
     raw = <<-RAW
 {{toc}}