Brother MFC-J825DW - Manual (Page 141)

Printing and Faxing
132
8
Duplex Printing
8
 Automatic Duplex Printing (For MFC-J625DW/J825DW/J835DW/J5910DW)
a Select Layout.
b Choose Long-edge binding or Short-edge binding in Two-Sided.
Note
The Borderless feature is not available for duplex printing.