Canon DADF-Q1 Service Manual page 64

Chapter 2
b. Sequence of Operation (fax/SEND; double-sided original)
F-2-99
c. Printing (double-sided original)
1) The machine picks up the 1st original, and butts its lead edge against the registration roller to remove the skew. (For details of pickup operation, see 'Original
Pickup/Separation.')
1st original
Registration roller
F-2-100
2-42