diff --git a/src/calibre/gui2/actions/__init__.py b/src/calibre/gui2/actions/__init__.py
index 7b07cdf732..fa67130a1c 100644
--- a/src/calibre/gui2/actions/__init__.py
+++ b/src/calibre/gui2/actions/__init__.py
@@ -180,30 +180,30 @@ class InterfaceAction(QObject):
             description=None, triggered=None, shortcut_name=None):
         '''
         Convenience method to easily add actions to a QMenu.
+        Returns the created QAction, This action has one extra attribute
+        calibre_shortcut_unique_name which if not None refers to the unique
+        name under which this action is registered with the keyboard manager.
 
         :param menu: The QMenu the newly created action will be added to
         :param unique_name: A unique name for this action, this must be
-        globally unique, so make it as descriptive as possible. If in doubt add
-        a uuid to it.
+            globally unique, so make it as descriptive as possible. If in doubt add
+            a uuid to it.
         :param text: The text of the action.
         :param icon: Either a QIcon or a file name. The file name is passed to
-        the I() builtin, so you do not need to pass the full path to the images
-        directory.
+            the I() builtin, so you do not need to pass the full path to the images
+            directory.
         :param shortcut: A string, a list of strings, None or False. If False,
-        no keyboard shortcut is registered for this action. If None, a keyboard
-        shortcut with no default keybinding is registered. String and list of
-        strings register a shortcut with default keybinding as specified.
+            no keyboard shortcut is registered for this action. If None, a keyboard
+            shortcut with no default keybinding is registered. String and list of
+            strings register a shortcut with default keybinding as specified.
         :param description: A description for this action. Used to set
-        tooltips.
+            tooltips.
         :param triggered: A callable which is connected to the triggered signal
-        of the created action.
+            of the created action.
         :param shortcut_name: The test displayed to the user when customizing
-        the keyboard shortcuts for this action. By default it is set to the
-        value of ``text``.
+            the keyboard shortcuts for this action. By default it is set to the
+            value of ``text``.
 
-        :return: The created QAction, This action has one extra attribute
-        calibre_shortcut_unique_name which if not None refers to the unique
-        name under which this action is registered with the keyboard manager.
         '''
         if shortcut_name is None:
             shortcut_name = unicode(text)
diff --git a/src/calibre/manual/epub.py b/src/calibre/manual/epub.py
index a162303b09..1aadbe9f91 100644
--- a/src/calibre/manual/epub.py
+++ b/src/calibre/manual/epub.py
@@ -6,7 +6,9 @@ __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import os, time
+import os, time, glob
+
+from lxml import etree
 
 from sphinx.builders.epub import EpubBuilder
 
@@ -55,4 +57,38 @@ class EPUBHelpBuilder(EpubBuilder):
     def build_epub(self, outdir, *args, **kwargs):
         if self.config.epub_cover:
             self.add_cover(outdir, self.config.epub_cover)
+        self.fix_duplication_bugs(outdir)
         EpubBuilder.build_epub(self, outdir, *args, **kwargs)
+
+    def fix_duplication_bugs(self, outdir):
+        opf = glob.glob(outdir+os.sep+'*.opf')[0]
+        root = etree.fromstring(open(opf, 'rb').read())
+        seen = set()
+        for x in root.xpath(
+                '//*[local-name()="spine"]/*[local-name()="itemref"]'):
+            idref = x.get('idref')
+            if idref in seen:
+                x.getparent().remove(x)
+            else:
+                seen.add(idref)
+
+        with open(opf, 'wb') as f:
+            f.write(etree.tostring(root, encoding='utf-8', xml_declaration=True))
+
+
+        ncx = glob.glob(outdir+os.sep+'*.ncx')[0]
+        root = etree.fromstring(open(ncx, 'rb').read())
+        seen = set()
+        for x in root.xpath(
+                '//*[local-name()="navMap"]/*[local-name()="navPoint"]'):
+            text = x.xpath('descendant::*[local-name()="text"]')[0]
+            text = text.text
+            if text in seen:
+                x.getparent().remove(x)
+            else:
+                seen.add(text)
+
+        with open(ncx, 'wb') as f:
+            f.write(etree.tostring(root, encoding='utf-8', xml_declaration=True))
+
+