If you want to have more than 1 FeedbackPanel on a page, but don't want to show errors messages in both at the same time use the following to filter the messages.

 FeedbackPanel feedbackPanel = new FeedbackPanel("feedback");
 feedbackPanel.setFilter(new IFeedbackMessageFilter() {
     public boolean accept(FeedbackMessage message) {
         if (message.getReporter().getParent() h1.  YourForm.this) {
             return true;
         }
         return false;
    }
 });
 add(feedbackPanel);

The line

if (message.getReporter().getParent() YourForm.this) {

will check to see if the reporting form component is from the form you added your FeedbackPanel to.