Duplex Scanning in OSX with non-duplex scanner with document feeder

How can I scan a large double sided document with my scanner's document feeder? The scanner only can scan one side of the page. However, I am bulk scanning all my bills and tax forms and have several that are 10+ pages with text on both sides of the page.

Is there any stock software that will scan one side, prompt for you to flip the pages, scan the other side, and them output a single PDF file? Otherwise, I would need software to simply combine the two PDF files and properly order the pages.

There is also a free alternative with PDFSAM, that perfectly work on Sierra 10.12.4.

You can separately scan first odd pages (beginning with the first page) and then even pages (beginning from the last page). After that you can mix all together with the alternate mix option taking care of reverse the even page, as the following image:

PDF Scanner app on the app store claims to have 'fake duplex' scanning, which allows dual sided document scanning without a duplex scanner.

http://www.pdfscannerapp.com/

The "fake duplex" in PDF Scanner works very nicely.

The things I find frustrating are:

• Autocrop pages doesn't crop all pages in the batch the same. Sometimes it crops too much, so I avoid using Autocrop.

• Yellowed pages come out with a yellow background - There doesn't seem to be a means of setting the white level.

• It works very well with the HP LaserJet series 200 document feeder. On the flatbed, there is a delay in scanning. So if scanning flatbed, I use the HP supplied software. For fake duplex I use this.