duplicate listener: AbstractJpaProject.ResourceModelListener[00-32-60-DB](HibernateJpaProject[01-74-D9-59](poh5))

java.lang.IllegalArgumentException: duplicate listener: AbstractJpaProject.ResourceModelListener[00-32-60-DB](HibernateJpaProject[01-74-D9-59](poh5))
	at org.eclipse.jpt.common.utility.internal.ListenerList.add(ListenerList.java:95)
	at org.eclipse.jpt.jpa.core.resource.xml.JpaXmlResource.addResourceModelListener(JpaXmlResource.java:264)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject.addJpaFileMaybe_(AbstractJpaProject.java:579)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject.addJpaFileMaybe(AbstractJpaProject.java:552)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject.synchronizeJpaFiles(AbstractJpaProject.java:1683)
	at org.jboss.tools.hibernate.jpt.core.internal.HibernateJpaProject.synchronizeJpaFiles(HibernateJpaProject.java:254)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject$InternalResourceDeltaVisitor.fileChangeIsSignificant(AbstractJpaProject.java:1668)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject$ResourceDeltaVisitor.fileChanged(AbstractJpaProject.java:1860)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject$ResourceDeltaVisitor.visit(AbstractJpaProject.java:1852)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:69)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:49)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject$ResourceDeltaVisitor.visitDelta(AbstractJpaProject.java:1835)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject.internalProjectChanged(AbstractJpaProject.java:1646)
	at org.eclipse.jpt.jpa.core.internal.AbstractJpaProject.projectChanged(AbstractJpaProject.java:1638)
	at org.eclipse.jpt.jpa.core.internal.InternalJpaProjectManager.projectChanged_(InternalJpaProjectManager.java:684)
	at org.eclipse.jpt.jpa.core.internal.InternalJpaProjectManager$ProjectChangeEventHandlerCommand.execute(InternalJpaProjectManager.java:670)
	at org.eclipse.jpt.common.core.internal.utility.command.JobCommandJob.run(JobCommandJob.java:42)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)