$a = Array(
  Array(
    'wanjiaid' => '2',
    'address' => '发生到了附近的',
    'mobile' => '15810444878',
    'user_name' => '王佳琳',
  ),
  array(
    'wanjiaid'=>'3',
    'address' => '发生到了附近的',
    'mobile' => '15810444878',
    'user_name' => '王佳琳',
  ),
  array(
    'wanjiaid'=>'4',
    'address' => '发生到了附近的2',
    'mobile' => '15424887895',
    'user_name' => '王佳琳1',
  ),
  array(
    'wanjiaid'=>'5',
    'address' => '发生到了附近的2',
    'mobile' => '15810444878',
    'user_name' => '王佳琳2',
  ),
  array(
    'wanjiaid'=>'6',
    'address' => '山东福彩',
    'mobile' => '12548888888',
    'user_name' => '王佳琳3',
  ),
);
$res = array();
$st = array(
  'address' => array(),
  'mobile' => array(),
  'user_name' => array(),
);
foreach($a as $t) {
  $flag = true;
  foreach($st as $k=>$v) {
    if(in_array($t[$k], $v)) $flag = false;
    $st[$k][] = $t[$k];
  }
  if($flag) $res[] = $t; 
}
print_r($res);