Epson Stylus Color 980 Manual page 34

For Windows users, select the Double-Sided Printing check box
on the Layout menu of your printer driver to use the double-sided
printing feature. To access your printer driver, see "Accessing the
printer software" on page 3-2.
For Macintosh users, select the Double-Sided Printing check box
in the Page Setup dialog box. For information on making settings
in this dialog box, see "Making Changes to Printer Settings" on
page 5-2.
2-2
Double-Sided Printing