If your scanner can only scan one side of a document at a time then give this Automator
work flow a try Combine Odd and Even Scans
It needs two files as input.
- The front pages of the document, scanned in normal order
- The back pages of the document, scanned in reverse order
To get the back pages scanned in reverse order simply take the scanned pile of front pages and flip it over before inserting it back into the scanner. This will scan the back of the last page first working through to the back of the first page.
The work flow will take the two files, reshuffle and combine them to give you the a copy of the scanned document with the pages all in the correct order.