Atunah, you could do as daffy is doing and it would likely be ok.
However, if it was me, I'd call just to avoid any potential confusion as each mailing label is specific to the order. It says this on Amazon's website:
Each return mailing label is uniquely assigned to a specific return. In order to ensure that you receive the correct refund, please do not include items from other orders or other shipments in the same box. Every shipment must be returned using a separate mailing label.
In any case, I hope your replacement works out better for you.