When creating invoices from the Create page, you can choose to create more than one invoice in one session by selecting multiple rows.
Holding the 'ctrl' on your keyboard down, select the rows you want to create invoices for by clicking on the rows. Selected rows will highlight in blue. Alternatively, you can also click on the check boxes to select rows you want to create invoices from.

Once you have selected the invoices you would like to create, click the 'Create Invoice' button on the top right corner of the screen.

You will then be brought to the details view of the first invoice, enter the coding details for that invoice. Click the 'Save and Next' button to be brought to the next invoice for coding.