All payment confirmation screens provide links for printing or emailing a Sales Receipt but you can also generate duplicate or updated Sales receipts/invoices for one or more specific orders from the Orders page.  During your Gala event, you can use a shortcut from the Auction Night Screen to navigate to the Orders page to produce duplicate receipts.

You can also generate a consolidated receipt for all purchases for a user (or a couple with separate records) from the User page.

Note:  The Sales receipt/invoice format is the same and the software generates the appropriate label based on whether the order has been paid in full or not.   Instructions for setting up your Sales/Guest receipt can be found here.