eCommerce - Add Support for adding some Cart Details including total Price to Checkout Page/ Form

Jayne Cooter requested this and I've been able to re-create.
Good afternoon, I'm trying to show the total amount on an ecommerce checkout but for some reason it seems to be doubling up on the quantity, are you able to help please?
The Liquid below works on a Cart view, but not on a Checkout
{%- include 'ecommerce/pricetotal', formattype: 'formatted' -%}
Furthermore, outputting a Cart Layout on the same Page as a Checkout Form shows a Liquid error.