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Duplex scanning is a feature of some computer scanners, and 
Duplex scanning is usually implemented on multifunction printers using a '' Reversing Automatic Document Feeder'' (RADF), which removes, reverses, and re-feeds the document after scanning one side. Duplex scanning is achieved on scanners by either RADF or by single pass duplex scanning using two cameras, one for each side of document; two-camera scanners scan twice as fast as a similar two-pass scanner.
multifunction printer
An MFP (multi-function product/printer/peripheral), multi-functional, all-in-one (AIO), or multi-function device (MFD), is an office machine which incorporates the functionality of multiple devices in one, so as to have a smaller footprint in a ...
s (MFPs) that support duplex printing
Duplex printing is a feature of some computer printers and multi-function printers (MFPs) that allows the printing of a sheet of paper on both sides automatically. Print devices without this capability can only print on a single side of paper, s ...
. A duplex scanner can automatically scan a sheet of paper on both sides. Scanners without this capability can only scan both sides of a sheet of paper by reinserting it manually the other way up.
Duplex scanning is usually implemented on multifunction printers using a '' Reversing Automatic Document Feeder'' (RADF), which removes, reverses, and re-feeds the document after scanning one side. Duplex scanning is achieved on scanners by either RADF or by single pass duplex scanning using two cameras, one for each side of document; two-camera scanners scan twice as fast as a similar two-pass scanner.
Typical duplex scanners
The following table compares features for a number of duplex scanners, mostly discontinued as of 2015:References