Keep sheet count and face count separate
A front batch of 40 pages and a back batch of 40 pages is consistent with 40 two-sided sheets, provided every face was retained. It does not show that each back is paired with the correct front. If blank backs were removed, the position of every later back can shift.
Keep blank-page removal disabled when positional front/back pairing matters, or retain an explicit list of omitted faces. Equal counts alone are not enough: the scanner could have repeated one face and skipped another.
Test the back-feed direction
Some workflows produce backs in the opposite order to the fronts. Choose whether the first or last back belongs with the first front. Scan Coverage interleaves a report view with sheet and face information; it never writes a reordered PDF.
- Inspect the first sheet, a middle sheet and the final sheet against the physical stack.
- Use printed numbers as supporting evidence, including odd/even expectations where the source uses them.
- Check all unexpected reversals and repeated labels.
- Use the output-page index from the combined ledger for corrections.
Resolve resets before moving pages
Front matter may use Roman numerals and a chapter may start again at 1. Those changes can resemble reversed order. Declare intentional section starts and rerun the check before planning a new PDF. A valid source can also contain foldouts or inserts outside the normal numbering sequence.
After choosing a documented order, perform any actual rearrangement in a trusted local PDF editor. Keep the original front and back batches so that a mistaken ordering decision can be reversed.