This message is automatically generated in Home Depot's system (this could include Home Depot, Home Depot Canada and HD Supply) when they receive what would be considered a duplicate Ship Notice. This could be due to having already sent a Ship Notice with that number or sending a second Ship Notice on the same Purchase Order. Before you send a Ship Notice, you may want to check that no other Ship Notice has the number you are using. In WebForms, you can do this using the Show Find feature, searching by the ID field. You may also want to ensure that you have not already sent a Ship Notice from the Order that you're sending from. In WebForms, you can do this by clicking on Next Steps, and then selecting Related Documents.
If you were trying to send a correction to a Ship Notice, you should know that Home Depot logs information about every Ship Notice that comes into their system. Their system will automatically accept only the first Ship Notice and reject any subsequent ones. If you need to re-send a document, and you do not want it to be rejected by Home Depot, you may wish to contact them to purge the original document from their system before you proceed.