When going to print, select the printer and click the Preferences button. Make sure the following two options are set to "1-sided".
macOS 11.x and Later
When printing, change the drop-down to "Printer Features". Then select "Finishing Options" from the Feature Sets drop-down, and make sure the Print Type is set to "1-Sided".
If you do not see the "Printer Features" option, you may not have the correct Konica Minolta driver package installed.
macOS 10.x and Earlier
When going to print, click the "Show Details" button.
After that, select "Printer Features", then "Finishing Options", and make sure the Print Type is set to "1-Sided".