Hi,
We do that because PayPal doesn't support taxes on the shipping fees and HikaShop does. So we have to put the shipping fees as a product line, otherwise, we wouldn't be able to add the tax on the shipping and the total would be wrong and it wouldn't work.
What you can do is change the code:
$vars['item_name_' . $i] = JText::_('HIKASHOP_SHIPPING');
$vars['amount_' . $i] = round($order->order_shipping_price - @$order->order_shipping_tax, (int)$this->currency->currency_locale['int_frac_digits']);
$tax += round($order->order_shipping_tax, (int)$this->currency->currency_locale['int_frac_digits']);
$vars['quantity_' . $i] = 1;
$i++;
to:
$vars['shipping'] = round($order->order_shipping_price, (int)$this->currency->currency_locale['int_frac_digits']);
in the file plugins/hikashoppayment/paypal/paypal.php
However, that means that if you have taxes on shipping, it will probably not work properly.