private void insertMessages(List<Message> newMessages) {
    		if ( newMessages == null ) return;
    		
    		for (Message msg : newMessages) {
    			if ( type == QueueType.REDUCE )  {  // only perform duplicate detection for reduce queues
    				if ( committedMap == null )
    					logger.fatal("CommittedMap cannot be empty");
        			String body = msg.getBody();
        			int idx = body.indexOf(':');
	    			String tag = body.substring(0, idx);
	    			String newbody = body.substring(idx+1);
	    			String committer = tag.substring(0, tag.lastIndexOf('_'));
	    			if (!committedMap.contains(committer))
	    				logger.info("Discard un-committed Map result from " + committer);
	    			else if (receivedMsg.contains(tag))
	    				logger.info("Found duplicate message " + tag + " in reduce queue " + name);
	    			else
	    			{
	    				receivedMsg.add(tag);
	    				msg.setBody(newbody);  // change body to stripped down real content
	    				messages.add(msg);
	    			}
    			}
    			else
    				messages.add(msg);
    		}
    	}