How do I move a view display from a view to another one?
This is tricky, but you can export both views to code and then add the desired display manually to the View.

In your case:


First export User view and Flags views



The exported views should be something like this:

$view = new view();
$view-&gt;name = 'frontpage';
$view-&gt;description = 'Emulates the default Drupal front page; you may set the default home page path to this view to make it your front page.';
$view-&gt;tag = 'default';
$view-&gt;base_table = 'node';
$view-&gt;human_name = 'Front page';
$view-&gt;core = 0;
$view-&gt;api_version = '3.0';
$view-&gt;disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Master */
$handler = $view-&gt;new_display('default', 'Master', 'default');
$handler-&gt;display-&gt;display_options['use_more_always'] = FALSE;
$handler-&gt;display-&gt;display_options['access']['type'] = 'perm';
$handler-&gt;display-&gt;display_options['cache']['type'] = 'none';
$handler-&gt;display-&gt;display_options['query']['type'] = 'views_query';
$handler-&gt;display-&gt;display_options['query']['options']['query_comment'] = FALSE;
$handler-&gt;display-&gt;display_options['exposed_form']['type'] = 'basic';
$handler-&gt;display-&gt;display_options['pager']['type'] = 'full';
$handler-&gt;display-&gt;display_options['style_plugin'] = 'default';
$handler-&gt;display-&gt;display_options['row_plugin'] = 'node';
/* Sort criterion: Content: Sticky */
$handler-&gt;display-&gt;display_options['sorts']['sticky']['id'] = 'sticky';
$handler-&gt;display-&gt;display_options['sorts']['sticky']['table'] = 'node';
$handler-&gt;display-&gt;display_options['sorts']['sticky']['field'] = 'sticky';
$handler-&gt;display-&gt;display_options['sorts']['sticky']['order'] = 'DESC';
/* Sort criterion: Content: Post date */
$handler-&gt;display-&gt;display_options['sorts']['created']['id'] = 'created';
$handler-&gt;display-&gt;display_options['sorts']['created']['table'] = 'node';
$handler-&gt;display-&gt;display_options['sorts']['created']['field'] = 'created';
$handler-&gt;display-&gt;display_options['sorts']['created']['order'] = 'DESC';
/* Filter criterion: Content: Promoted to front page */
$handler-&gt;display-&gt;display_options['filters']['promote']['id'] = 'promote';
$handler-&gt;display-&gt;display_options['filters']['promote']['table'] = 'node';
$handler-&gt;display-&gt;display_options['filters']['promote']['field'] = 'promote';
$handler-&gt;display-&gt;display_options['filters']['promote']['value'] = '1';
$handler-&gt;display-&gt;display_options['filters']['promote']['group'] = 0;
$handler-&gt;display-&gt;display_options['filters']['promote']['expose']['operator'] = FALSE;
/* Filter criterion: Content: Published */
$handler-&gt;display-&gt;display_options['filters']['status']['id'] = 'status';
$handler-&gt;display-&gt;display_options['filters']['status']['table'] = 'node';
$handler-&gt;display-&gt;display_options['filters']['status']['field'] = 'status';
$handler-&gt;display-&gt;display_options['filters']['status']['value'] = '1';
$handler-&gt;display-&gt;display_options['filters']['status']['group'] = 0;
$handler-&gt;display-&gt;display_options['filters']['status']['expose']['operator'] = FALSE;

/* Display: Page */
$handler = $view-&gt;new_display('page', 'Page', 'page');
$handler-&gt;display-&gt;display_options['path'] = 'frontpage';

/* Display: Feed */
$handler = $view-&gt;new_display('feed', 'Feed', 'feed');
$handler-&gt;display-&gt;display_options['defaults']['title'] = FALSE;
$handler-&gt;display-&gt;display_options['title'] = 'Front page feed';
$handler-&gt;display-&gt;display_options['pager']['type'] = 'some';
$handler-&gt;display-&gt;display_options['style_plugin'] = 'rss';
$handler-&gt;display-&gt;display_options['row_plugin'] = 'node_rss';
$handler-&gt;display-&gt;display_options['path'] = 'rss.xml';
$handler-&gt;display-&gt;display_options['displays'] = array(
  'default' =&gt; 'default',
  'page' =&gt; 'page',
);
$handler-&gt;display-&gt;display_options['sitename_title'] = '1';


As you can see, first you have the general View config, and then the definition and config for each view's displays.


Then you have to select the code regarding your display in User view and copy to the code of the Flag view, so you end with a Flag view with an added display. 
Using the import functionality of Views import the modified view.




If everything is ok, Views will import your modified view with the added display.

The two views should be similar (they should show similar content, for example).