Bug 153853 [Regression]The bound column names must be unique within the entire table.
Regression case Regression_136421(under org.eclipse.birt.report.tests.model) failed. Expected result: Model will avoid adding a duplicate bound column name within a table.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/elements/ReportItem.java
implements
			IReportItemModel
{
	/**
	 * Default constructor.
	 */
	public ReportItem( )
	{
	}
	/**
	 * Constructs the report item with an optional name.
	 * 
	 * @param theName
	 *            the optional name
	 */
	public ReportItem( String theName )
	{
		super( theName );
	}
	/**
	 * Returns the data set element, if any, for this element.
	 * 
	 * @param module
	 *            the report design of the report item
	 * 
	 * @return the data set element defined on this specific element
	 */
	public DesignElement getDataSetElement( Module module )
	{
		ElementRefValue dataSetRef = (ElementRefValue) getProperty( module,