HP Color LaserJet Enterprise CP4525 Printer series - Manual (Page 135)

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 place it with the printed-side facing up 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
NOTE: This information applies only to products that have an automatic duplexer.
1. On the File menu in the software program, click
Print.
ENWW Print with Windows 121