usort($mass, function ($a, $b) {
    if ($a == $b) {
    $int = random_int(-1, 1);
    return $int;
    } else {
     return $a < $b ? -1 : 1;
   }
  })

$array = [
    "apple" => "5",
    "avocado" => "15",
    "apricot" => "1",
    "banana" => "5",
    "plum" => "12",
    "pineapple" => "5"
];

$keys = array_keys($array);
shuffle($keys);
array_map(function($k)use($array, &$arr){ $arr[$k] = $array[$k]; }, $keys);
uasort($arr, function($a, $b){ return $a <=> $b; });

var_dump($arr);