Does the print driver know the printer has a duplex unit? Can't you select "2-sided" in the driver or is it that you're selecting it but it's ingnoring the request. If you can't see the option it may not see there's a duplex unit installed. Make sure you have bi-directional enabled on the driver so it's talking to the printer in regards to installable options.
Thank you for using the Xerox forum.
I do not understand the question completely.
I can not find a 3375. What printer model are you having a problem with?
Once we know which model I would suggest reviewing the Xerox product support site which has many downloads and tips for each model.
I unable to print in double-sided from unix after installed ApeosPort-V C3375 (x64 PCL Windows WHQL Driver & PPD file format).Please advice.