$id_curency - id валюты из админки
$currency = new Currency($id_curency);
$amount = number_format(Tools::convertPrice(цена товара, $currency), 2, '.', '')

<span class="price" style="display: inline;">{convertPriceWithCurrency price=$product.price_1 currency=1}</span><br />
<span class="price" style="display: inline;">{convertPriceWithCurrency price=$product.price_2 currency=2}</span><br />

$cat_products = $category->getProducts(intval($cookie->id_lang), intval($p), intval($n), $orderBy, $orderWay);

$ret_arr = array();
foreach ($cat_products as $cat_product) {
  $curen_1 = new Currency(1);
  $curen_2 = new Currency(2);
  $cat_product['price_1'] = Tools::convertPrice($cat_product['price'],$curen_1);
  $cat_product['price_2'] = Tools::convertPrice($cat_product['price'],$curen_2);
  $ret_arr[] = $cat_product;
}
  $cat_products = $ret_arr;