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/api/ModuleHandle.java
/**
	 * The flag indicates that whether the initialization is finished.
	 */
	protected boolean isInitialized = false;
	/**
	 * Constructs one module handle with the given module element.
	 * 
	 * @param module
	 *            module
	 */
	public ModuleHandle( Module module )
	{
		super( module );
	}
	/**
	 * Adds a new config variable.
	 * 
	 * @param configVar
	 *            the config variable
	 * @throws SemanticException
	 *             if the name is empty or the same name exists.
	 * 
	 */
	public void addConfigVariable( ConfigVariable configVar )
			throws SemanticException
	{
		ElementPropertyDefn propDefn = module
				.getPropertyDefn( CONFIG_VARS_PROP );
		if ( configVar != null && StringUtil.isBlank( configVar.getName( ) ) )
		{