How to get Duplicate SKU products in Magento

I want to fetch all duplicate sku code in my Magento store.

Many products have same sku code with different entity_id.

Below is my query,

But it returns only first row, then I write sql again to search by sku code. but it still returns first row only.

<?php 
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
set_time_limit(0);
require_once '/var/www/html/app/Mage.php';
umask(0);

Mage::app('default');

$connection = Mage::getSingleton('core/resource')->getConnection('core_write');

$selectsku = "select entity_id, sku, COUNT(*) as count from catalog_product_entity GROUP BY sku HAVING (COUNT(*) > 1) LIMIT 10";
$selectskuresult = $connection->query($selectsku);
$resultquery = $selectskuresult->fetch();
//print_r($resultquery);

$sku = $resultquery['sku'];
//echo $sku;
$counter = 1;
while($counter < 10)
    {
        $selectentityid = "select entity_id, sku from catalog_product_entity where sku = '".$sku."'";
        $selectentityidresult = $connection->query($selectentityid);
        $resultquery = $selectentityidresult->fetch();
        print_r($resultquery);
        $counter++;
    }

?>

Please provide some guidance for fetch all rows. I have applied while loops still its not working as expected.