Brother MFC-J825DW - Manual (Page 142)

Printing and Faxing
133
8
 Manual Duplex Printing (For MFC-J280W/J425W/J430W/J435W)
The machine prints all the even-numbered pages on one side of the paper first. Before reinserting the
paper, straighten it well, or you may get a paper jam. Very thin or very thick paper is not recommended.
a
Select Paper Handling.
b
(Mac OS X 10.4.11)
Choose Even numbered pages and print, and then choose Odd numbered pages and print.
(Mac OS X 10.5.x to 10.6.x)
Choose Even Only and print, and then choose Odd Only and print.