How to Merge Alternating Pages from Two Scanned PDFs (Fixing Duplex Scans)
Written and fact-checked by The EditPDF AI Team
Scanning a double-sided document on a single-sided (simplex) scanner typically produces two separate files — all front pages in order, then all back pages, often in reverse order. Getting a normal front-back-front-back reading order takes a few extra steps, since there is no single "interleave" button for this.
Why does this happen with duplex documents?
A simplex scanner can only capture one side of the paper per pass. The standard workaround is to scan all the fronts face-up, flip the whole stack, then scan all the backs — which usually come out in reverse order, since the last page scanned face-up becomes the first page flipped over. The result is two files that need to be woven together, not just appended one after the other.
How to interleave the pages correctly
- 1If your back-pages file is in reverse order, use Rotate PDF or Page Manager to reverse its page order first, so page 1 of the backs file lines up with page 1 of the fronts file.
- 2Split both files into individual single-page files using PDF Splitter, so each page exists as its own file.
- 3Use PDF Merger and add the files in the exact order you want them read: front 1, back 1, front 2, back 2, and so on.
- 4Download the merged result and check the page order before discarding either original file.
There is no dedicated "interleave" or "alternate merge" mode today — this sequence of three tools gets you the same result, just with a manual reordering step in the middle.
A faster option if you're scanning fresh
If you haven't scanned yet and have a choice, capturing pages directly with Scan to PDF in the actual reading order (front, back, front, back) avoids this problem entirely — the interleaving issue only comes up because a simplex scanner's workflow forces fronts and backs apart in the first place.
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