Due to a limitation in the print software upon which LockLizard is based, automatic duplexing is not available at this time. You can, however, change your print settings to print only odd pages and then flip the stack over and print the even pages. Test on a small subset of pages (like pages 1-4) to make sure you will print them in order. Your printer may require you to check the "Reverse" button on one or the other print jobs, depending on the way the paper feeds into your printer.