HP L7680 mirroring
This affects all L7000 series Inkjet multifunctionals (L7580, L7780) so hopefully this will save a few folks this "fun".
There is an issue with the driver and the built-in "duplex" (double-sided) quick setting which, for some bizzare reason seems to be set to use "mirror" as one of the advanced settings.
I can't be 100% sure but it seems that the latest 8.0.1 drivers may resolve this but I've already found the hard way that you can install the driver but it won't fix the setting for any pre-installed printers. The only way I've found to fix the problem is to delete the existing printers and re-detect them.
Even having said that I can't be 100% sure this does indeed resolve things as I've not had a chance to test the theory on new machines.
HP are, as per usual blissfully ignoring the problem while more and more reports are appearing. As far as I know though the issue is restricted to these printers and the quick settings but it may apply elsewhere.