Form api treats multiple submit buttons wrong.

If two submit buttons have same values, the first button will be treated as the second button..

/**
 * Problems:
 * When I click the first 'Submit' button, it shows "Hello1"!
 * I.e, when I click the first button, drupal think treats the trigger
 * button as the second submit button!
 * If I change the first button's value to "Button", or whatever different
 * from the second button's value "Submit", then it works fine.
 */

function agl_jira_new_test_form($form, &$form_state) {

  $form['textfield_1_1'] = array(
    '#title' => t('name'),
    '#type' => 'textfield',
    '#required' => TRUE,
  );
  $form['textfield_2'] = array(
    '#title' => t('name2'),
    '#type' => 'textfield',
    '#required' => TRUE,
  );

  $form['button'] = array(
    '#type' => 'submit',
    '#value' => 'Submit',
    '#limit_validation_errors' => array(array('textfield_1_1')),
    '#submit' => array('agl_jira_new_test_form_submit'),
  );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => 'Submit',
    '#submit' => array('agl_jira_new_test_form_submit1'),
  );
  return $form;
}
function agl_jira_new_test_form_submit($form, &$form_state) {
  // do something.
  dsm('Hello');
  $form_state['rebuild'] = TRUE;
}

function agl_jira_new_test_form_submit1($form, &$form_state) {
  // do something.
  dsm('Hello1');
  $form_state['rebuild'] = TRUE;
}

Any help will be appreciated!