title: How to enable duplex printing on HP 7610 with Linux (Ubuntu 13.04)
body: <p>I have equipped my HP 7610 printer with the duplex extension, but the configuration dialogs of Ubuntu and Kubuntu still have the duplex option greyed out. Even re-installing the printer does not help. It seems the printer doesn't tell the computer that it is capable of duplex printing now, still the same configuration is used.</p>
  
  <p>Is there a way of enabling duplex printing for this model?</p>
  
  <p>Would it help to add somethig to the PPD file? What would this extension look like?</p>