When you scan a double-page spread book with SV600, both the left and right sides are scanned. You cannot specify the pages to be scanned.
If you only need the left or right side of a double-page spread book, scan the book with SV600, split the double-page spread images into left and right images, and then delete the images for the undesired side in ScanSnap Home.
For details:
ScanSnap Help