There have been previous Posts that described out to unimpose a Reader Spread using Split and Route components. These components are part of the Advanced Automation option. Here is a method using page ranges of the Duplicate and Resize components, which are included with Advanced Prepress.
First the original file:
The workflow is:
As the names imply each node will only modify the center pages by using a page range of 2 to -2 (2nd to the last page). Remember that -1 refers to the last page in a document. The first and last page will be unaffected.
Since each page will be cropped in half and both halves are needed, duplicate the center pages:
Then using Resize, crop the Even pages starting with the 2nd page until the 2nd to last page and only keep the left half.
Now using Resize, crop the Odd pages starting with the 2nd page until the 2nd to last page and only keep the Right half.
The final result are 1 up PDF file pages:
Attached is the FreeFlow Core 5.1 FFC file (in a ZIP) that can be imported using Core Exchange. And a sample PDF File.
The workflow includes Pause nodes that can be removed after validation on your system.