HP 5550 and Duplex

[Thierry Thévoz <thierry thevoz smartdata ch>]

Hello,

I'm running CUPS with a HP 5550 printer. it is configured and running 
properly.

Only one thing is disturbing me : evolution print dialog insists that 
Duplex is selected by default.
Duplex default in CUPS is off (and everywhere else also).

How can I setup libgnomeprint, so that Duplex is disabled by default?

I thank you in advance!
Thierry