To duplicate an invoice:

1. Open the invoice you want to copy
2. In the sidebar, find the "Actions" section
3. Click "Duplicate"
4. A new draft is created with the same line items and customer
5. Adjust the date, amounts, or details as needed and save

The duplicate keeps the reference number and the linked property from the original invoice, so you do not lose a purchase-order number or a rental object assignment.

Tip: This is great for similar invoices to the same customer, it saves re-entering all line items.