Find duplicates

<?php
$line = trim(fgets(STDIN));
$nums = explode(' ', $line);

$duplicatedValues2Count = [];
foreach ($nums as $num) {
    if (!isset($duplicatedValues2Count[$num])) {
        $duplicatedValues2Count[$num] = 1;
    } else {
        $duplicatedValues2Count[$num]++;
    }

    if ($duplicatedValues2Count[$num] === 2) {
        echo $num . ' ';
    }
}