Why is the second PDF reversed by default?
A flipped paper stack usually scans its back pages from last to first. The visible direction control lets you switch back to forward order.
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Alternate & Mix PDF Pages Locally
Rebuild double-sided documents from separate front and back scans. Mix two or more PDFs locally, reverse scanner output when needed and keep unmatched pages instead of dropping them.
local processing workbench
Drop files. Choose a tool. Download the result.
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AlternateAdd 2 PDFs
2+ PDFsMix PDF pages needs 2 PDFs. You have 0.
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selected operation
Alternate
Interleave odd and even scans with per-file direction and pace.
OutputOne PDF with pages interleaved from each source.
Dedicated Worker protectedLocal details
Add files to activate protected local processing.
Duplex scan presetFront pages forward, back pages reversed.
PDF 1 forward -> PDF 2 reverse -> repeat
Add the front scan first and the back scan second.
Extra selected pages stay at the end. Original files are never changed.
how it works
Short path, clear output.
- Add the front or odd-pages PDF first and the back or even-pages PDF second.
- Keep the second PDF reversed for the common flipped-stack scan, or change either direction.
- Mix locally and download one correctly interleaved PDF.
faq
Practical boundaries before you process a file.
What happens when the PDFs have different page counts?
VaultPDF alternates while pages are available, then keeps any remaining selected pages without dropping them.