I'm using rich:datascroller & rich:dataTable and getting following error

java.lang.IllegalStateException: duplicate Id for a component pageHeader
at org.ajax4jsf.application.AjaxStateManager$TreeStrutureNode.apply(AjaxStateManager.java:326)
at org.ajax4jsf.application.AjaxStateManager$TreeStrutureNode.apply(AjaxStateManager.java:348)
at org.ajax4jsf.application.AjaxStateManager.saveSerializedView(AjaxStateManager.java:236)
at com.sun.faces.taglib.jsf_core.ViewTag.doAfterBody(ViewTag.java:169)

Please let me know how to solve this.