TIL that TeXlive now includes pdfxup as a replacement for the good old pdfnup. Time to update my oldie shell alias alias p2x1="pdfnup --nup 2x1 --landscape --suffix '2x1' --batch ".
pdfxup
pdfnup
alias p2x1="pdfnup --nup 2x1 --landscape --suffix '2x1' --batch "