Hi,
I don't understand what you mean.
The URL index.php?option=com_hikashop&ctrl=checkout&Itemid=103 is a URL displaying your checkout page, with the cart view and other views displayed on it.
The URL index.php?option=com_hikashop&view=cart&layout=show is a URL displaying your current cart page.
Whether you remove the parameter &Itemid=103 from the first URL or not, the checkout page displays exactly the same on your website.
And it's normal that the checkout page and the cart page don't display the same thing since they are not the same thing.
Now, if you add the parameter &Itemid=103 to the URL index.php?option=com_hikashop&view=cart&layout=show there is a layout change due to your template settings but there is nothing you can do in HikaShop to prevent that. That's something to check with your template provider. But it doesn't seem that you're talking about this ?