passing arguments through from pdf2ps

Hey guys,

I'm having trouble with duplex printing when converting a file with
pdf2ps.  The pdf2ps man page seems to suggest that "options" are passed
to "gs".  I have been running pdf2ps with "-dDuplex", but this doesn't
seem to be working.

Some background, I print postscript files direct with "lpr" on OpenBSD,
which doesn't support forced duplexing.  However, it seems to work fine
with postscript that specifies duplexing.  I'm a little fuzzy on ps, so
apologies if I'm way off-base...

Thanks.