HP LaserJet Pro 300 Color MFP M375 - Manual (Page 133)

4. Select the Print on both sides (manually)
check box. Click the OK button to print the
first side of the job.
5. Retrieve the printed stack from the output bin,
and maintaining the same orientation, place it
with the printed side facing down in Tray 1.
6. On the control panel, press the OK button to
print the second side of the job.
Automatically print on both sides with Windows
1. On the File menu in the software program,
click Print.
ENWW Basic print tasks with Windows 117