Direct to Cart URL with double discount codes?

[metalmo]

Is there a tutorial on how to create a direct-to-checkout link that incorporates two discount codes?

I'd like to combine a % off discount with a free shipping discount code.

I understand this is the typical URL structure for a single discount, but I want to add a second discount code as well: 

https://your-store.myshopify.com/cart/[VARIANT-ID]:[QUANTITY]?payment=[PAYMENT-METHOD]&discount=[DISCOUNT-CODE]