actionCartDuplicate.php

<?php

// Attach module to hook
$this->registerHook('actionCartDuplicate');

// Run custom logic when the hook is triggered
public function hookActionCartDuplicate($params)
{
    $id_cart_old = $params['oldCartId'];
    $id_cart_new = $params['newCartId'];
    // custom logic to duplicate data related to the old cart
}