How to display each user once?

Thanks for quick response. I do not know if I have user as basetable. Here is export.

$view = new view;
$view->name = 'custom_userpoints_2';
$view->description = 'Most userpoints';
$view->tag = '';
$view->view_php = '';
$view->base_table = 'node';
$view->is_cacheable = FALSE;
$view->api_version = 2;
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */
$handler = $view->new_display('default', 'Defaults', 'default');
$handler->override_option('relationships', array(
  'uid' => array(
    'label' => 'Users',
    'required' => 1,
    'id' => 'uid',
    'table' => 'userpoints',
    'field' => 'uid',
    'relationship' => 'none',
  ),
));
$handler->override_option('fields', array(
  'name' => array(
    'label' => 'Name',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'target' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'empty' => '',
    'hide_empty' => 0,
    'empty_zero' => 0,
    'link_to_user' => 1,
    'overwrite_anonymous' => 0,
    'anonymous_text' => '',
    'exclude' => 0,
    'id' => 'name',
    'table' => 'users',
    'field' => 'name',
    'relationship' => 'none',
  ),
  'picture' => array(
    'label' => 'Picture',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'target' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'empty' => '',
    'hide_empty' => 0,
    'empty_zero' => 0,
    'exclude' => 0,
    'id' => 'picture',
    'table' => 'users',
    'field' => 'picture',
    'relationship' => 'none',
  ),
  'points' => array(
    'label' => 'Points',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'target' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'empty' => '',
    'hide_empty' => 0,
    'empty_zero' => 0,
    'set_precision' => FALSE,
    'precision' => 0,
    'decimal' => '.',
    'separator' => ',',
    'prefix' => '',
    'suffix' => '',
    'exclude' => 0,
    'id' => 'points',
    'table' => 'userpoints',
    'field' => 'points',
    'relationship' => 'none',
  ),
));
$handler->override_option('sorts', array(
  'points' => array(
    'order' => 'DESC',
    'id' => 'points',
    'table' => 'userpoints',
    'field' => 'points',
    'relationship' => 'none',
  ),
));
$handler->override_option('access', array(
  'type' => 'none',
));
$handler->override_option('cache', array(
  'type' => 'none',
));
$handler->override_option('items_per_page', 36);
$handler->override_option('distinct', 1);
$handler->override_option('style_plugin', 'grid');
$handler->override_option('style_options', array(
  'columns' => '6',
  'alignment' => 'horizontal',
));
$handler = $view->new_display('page', 'Page', 'page_1');
$handler->override_option('path', 'top-userpoints');
$handler->override_option('menu', array(
  'type' => 'none',
  'title' => '',
  'description' => '',
  'weight' => 0,
  'name' => 'navigation',
));
$handler->override_option('tab_options', array(
  'type' => 'none',
  'title' => '',
  'description' => '',
  'weight' => 0,
));

OK. I understand now. Basetable aka view type. I tried again with user view type and all working fine. Thanks for your help.