- array_search: documentation ( source)
- var_export: documentation ( source)
<?php
$unique = [null, '', .0, false, null, 0, '0.0', -.1, "\0", false];
$duplicated=array();
foreach($unique as $k=>$v) {
if( ($kt=array_search($v,$unique))!==false and $k!=$kt )
{ unset($unique[$kt]); $duplicated[]=$v; }
}
var_export($unique);
var_export($duplicated);