Test task

function checkArray(Array $originArray): bool
{
    //convert array to lowercase with save type
    $array = array_map(function($item) {
        return is_string($item) ? strtolower($item) : $item;
    }, $originArray);

    //calculate duplicates and return result
    foreach ($array as $item) {
        $duplicates = array_keys($array, $item, true);
        if (count($duplicates) % 2 == 0) {
            return true;
        }
    }

    return false;
}