If you are trying to duplicate an order and the order fails, it is probably because the gift (or print) that is being duplicated is out of stock at the moment.
The first step is to contact the Customer Happiness Manager to see if there are any extras in stock that can be used to fulfill the order. If the Manager says that there aren't, you then need to reach out to the customer and ask what gift they're like to replace it with (there's a macro for this) and offer some recommendations to help them out!
After they let you know, politely ask the CHM to go into Spree and add 1 to the stock of the Out of Stock item, solely for the purposes of duplication. Then, duplicate the build and change the gift to the new item that was selected. Make sure to Save!!
If the new item is not the same price as the original item that was paid for, you may need to issue a refund or request a payment. Reach out to the CHM for help with this (or look at the FAQ for how to issue a refund!)