Sharp MX-4100N Operation Manual page 258

COPIER
The "2-Sided to 2-Sided" and "2-Sided to 1-Sided" modes of automatic 2-sided copying cannot be used.
To cancel the slow scan mode setting...
Touch the [Slow Scan Mode] key in the screen of step 2 so that it is not highlighted.
System Settings (Administrator): Original Feeding Mode
This is used to have scanning always take place in slow scan mode.
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