Regardless of the product you are selling (including gift cards), it is required to have a corresponding SKU code. Please login to your e-commerce store and make sure there is a unique SKU code for all the products that you are selling.
Error: Product item number (XXXX) already exists in MYOB
This error message indicates you have two products in MYOB with the same SKU code. To resolve this error, login to your MYOB account and adjust the SKU code for one of the product.