I have the same problem with a similar history.
Under 08.04, duplex printing worked fine to a Xerox 5500 and a Xerox Phaser 8550DP.
After upgrading to 08.10, duplexing works on the 5500 but not the 8550DP, as tested by printing the same document through evince.
I have the same problem with a similar history.
Under 08.04, duplex printing worked fine to a Xerox 5500 and a Xerox Phaser 8550DP.
After upgrading to 08.10, duplexing works on the 5500 but not the 8550DP, as tested by printing the same document through evince.