lpr -S filenameshould work if the software controlling the printer supports singlesided printing. <!See detailed note dated 15 Mar 1996 to helpers@klinzhai> The rest of this page is left for others at Rutgers who may still be using Solaris printing software.
Solaris printing software is a little different from what you're used to under SunOS 4.1.x. You queue a print request with lp and dequeue one with cancel
The command to print a file singlesided under Solaris is
lp -ynoduplex -dprinter filenameMore information about lp is available as lp_options.