What I do:
- I use the internal viewer and press Cmd-P (Mac)
- The window opens, twosided (checkbox) is selected
and my printer: Samsung CLP-550
- message (edited) Process started: lp -d Samsung_CLP-550 -P 1-14 -o sides=one-sided -- "/Users/CORRECTPATH/paper-decision-making.pdf"
- the first mistake is sides=one-sided
- second the correct internal printer name is Samsung_CLP_550 (for lp -d )
I did not find a way to change this through preferences.