Discount doesn't apply if cart has 2 identical products with different properties

Shopify Discussion

Topic summary

A user attempted to apply two “Amount off products” discounts to the same product when it appears twice in the cart with different custom properties (added via JavaScript using _custom_time timestamps). While a single discount works fine, applying both simultaneously fails—only one discount applies at a time, with new coupon codes replacing previous ones.

Root Cause:
Shopify’s discount system has a documented limitation preventing multiple product-based discounts from being combined on the same product, regardless of different line item properties.

Status:
A community member referenced Shopify’s official documentation on discount combination limitations and requested clarification on the use case. The thread remains unresolved with no confirmed solution, though follow-up messages suggest the original poster may have found a workaround but hasn’t shared details or closed the discussion.

Summarized with AI on October 28. AI used: claude-sonnet-4-5-20250929.
1

I created two “Amount off products” discounts for a test product with the following configuration:

https://screenshots.ablecanyon.com/gnJ4gDBmnbP3WsNbKScj

In my theme, when I click the “Add to Cart” button, a JavaScript function adds custom options to the cart item using the following request:

fetch('/cart/add.js', {
                                            method: 'POST',
                                            headers: {
                                                'Content-Type': 'application/json'
                                            },
                                            body: JSON.stringify({
                                                quantity: 1,
                                                id: v_ic,
                                                properties: { '_custom_time': timestamp_r }
                                            })
                                        })

Everything works fine when I add a single etwet product to the cart. I can apply any of the discounts at checkout, and if I enter a different coupon, it replaces the previous one.

However, when I add a second etwet product to the cart (with a different _custom_time property) and try to apply both discounts simultaneously, it doesn’t work. Only one discount is applied at a time—entering a new coupon replaces the previous one.

Is there a way to apply both “Amount off products” discounts to the same product when it has different properties in the cart?

2

Hi @dmitry_5 , if both the discounts are product based and applicable to the same product, then only one of the discounts will be applicable to the product.

This is a limitation covered by Shopify on their documentation

Abel_Lesle_0-1739799451512.png
Abel_Lesle_0-1739799451512.png1029×789 75.2 KB

You can read about this limitation by following this help article

https://help.shopify.com/en/manual/discounts/combining-discounts/discount-combinations#examples

Can you share the use case behind combining two product type discounts on the same product ?

Regards

3

@dmitry_5 - if you found my answer to resolve your query - can you mark it as a solution so that others can easily find value from the same.

Thank you :slightly_smiling_face:

4

@dmitry_5 Since quite some time has passed since you raised this thread, I’m assuming you’ve already reached at a solution :slightly_smiling_face:

If so - can you please share the same and close this thread out so that others who stumble here might also find value.

Thank you for your time,