java.lang.IllegalArgumentException: more than one element with same name found
   at org.openide.xml.XMLUtil.findElement(XMLUtil.java:982)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$9.run(AntProjectHelper.java:926)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$9.run(AntProjectHelper.java:922)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.readAccess(DefaultMutexImplementation.java:252)
   at org.openide.util.Mutex.readAccess(Mutex.java:218)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.getConfigurationFragment(AntProjectHelper.java:922)
   at org.netbeans.spi.project.support.ant.ExtensibleMetadataProviderImpl.getConfigurationFragment(ExtensibleMetadataProviderImpl.java:79)
   at org.netbeans.modules.projectapi.AuxiliaryConfigImpl$1.run(AuxiliaryConfigImpl.java:91)
   at org.netbeans.modules.projectapi.AuxiliaryConfigImpl$1.run(AuxiliaryConfigImpl.java:84)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.readAccess(DefaultMutexImplementation.java:252)
   at org.openide.util.Mutex.readAccess(Mutex.java:250)
   at org.netbeans.modules.projectapi.nb.NbProjectManager$MutexImpl.readAccess(NbProjectManager.java:794)
   at org.openide.util.Mutex.readAccess(Mutex.java:218)
   at org.netbeans.modules.projectapi.AuxiliaryConfigImpl.getConfigurationFragment(AuxiliaryConfigImpl.java:84)
   at org.netbeans.modules.editor.bookmarks.BookmarksPersistence.loadProjectBookmarksImpl(BookmarksPersistence.java:275)
   at org.netbeans.modules.editor.bookmarks.BookmarksPersistence.access$400(BookmarksPersistence.java:81)
   at org.netbeans.modules.editor.bookmarks.BookmarksPersistence$4.run(BookmarksPersistence.java:253)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.readAccess(DefaultMutexImplementation.java:236)
   at org.openide.util.Mutex.readAccess(Mutex.java:260)
   at org.netbeans.modules.editor.bookmarks.BookmarksPersistence.loadProjectBookmarks(BookmarksPersistence.java:250)
   at org.netbeans.modules.editor.bookmarks.BookmarkManager$4.run(BookmarkManager.java:309)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)