Redesign the Add to Cart Feature from the Designer Page

When running through mock orders, to see what the customer experience is on our site, we ran into a bit of an issue. We noticed that if someone adds a t-shirt (for example) to the designer, and picks their color, makes a design and adds it to the cart, that there is really no way to pick another color and use the same design.

If you hit "Buy" then it pulls up a "Your Cart" page and shows you your order. If you then hit "Back and change the color of the garment, but keep the design the sane, and then proceed to hit the "Update" button, then it doesn't add more products to the cart, but instead overwrites the first garment order with the new one of a different color, instead of adding it to the previous one.

 I'd much rather have it so that when someone hits the "Update" button, that it adds the new changed product to the cart on top of the previous product, instead of overwriting it. There is a "Start New Design" button in the cart, but many ustomers would rather use the same design, but get the same product in a different color. The only way we figured out how to do that is to duplicate the first item into a second one, go back and change the color, and then update it. But, that is just way too unintuitive. Honestly, the whole thing is very poorly designed.