$arr = ['a'=>'aaa','b'=>'bbb','c'=>'aaa'];
$newArr = [];
foreach ($arr as $k=>$v){
if(!in_array($v,$newArr)){
$newArr[] = $v;
}
}
$arr = ['a'=>'aaa','b'=>'bbb','c'=>'aaa'];
$newArr = [];
foreach ($arr as $k=>$v){
if(!in_array($v,$newArr)){
$newArr[] = $v;
}
}