Invalid index name "KEY id", statement: 4, table: "phpbb_user_items"

SQL:
CREATE TABLE `phpbb_user_items` (
  `id` int(20) NOT NULL auto_increment,
  `user_id` int(20) NOT NULL default '0',
  `item_id` int(20) NOT NULL default '0',
  `item_name` varchar(32) NOT NULL default '',
  `item_l_desc` text NOT NULL,
  `item_s_desc` varchar(100) NOT NULL default '',
  `worn` tinyint(1) NOT NULL default '0',
  `die_time` int(20) NOT NULL default '0',
  `special` text NOT NULL,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `id` (`id`),
  KEY `item_id` (`item_id`),
  KEY `user_id` (`user_id`)
);