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.project.ui.ProjectUtilities.getOpenFilesUrls(ProjectUtilities.java:631)
   at org.netbeans.modules.project.ui.ProjectUtilities.openProjectFiles(ProjectUtilities.java:588)
   at org.netbeans.modules.project.ui.ProjectUtilities.openProjectFiles(ProjectUtilities.java:581)
   at org.netbeans.modules.project.ui.OpenProjectList$25.run(OpenProjectList.java:1383)
   at org.openide.util.RequestProcessor$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)