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
* @return <code>true</code> if the design has changed since the last load
	 *         or save; <code>false</code> if it has not changed.
	 */
	public boolean needsSave( )
	{
		String version = module.getVersionManager( ).getVersion( );
		if ( version != null )
		{
			List versionInfos = ModelUtil.checkVersion( version );
			if ( !versionInfos.isEmpty( ) )
				return true;
		}
		return module.isDirty( );
	}
	/**
	 * Calls to inform a save is successful. Must be called after a successful
	 * completion of a save done using <code>serialize</code>.
	 */
	public void onSave( )
	{
		module.onSave( );
	}
	/**
	 * Removes a given validation listener. If the listener not registered, then
	 * the request is silently ignored.
	 * 
	 * @param listener
	 *            the listener to de-register
	 * @return <code>true</code> if <code>listener</code> is sucessfully
	 *         removed. Otherwise <code>false</code>.