Since I upgraded to Vivid I get exactly the same issue Nils mentioned here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1296270/comments/25 and I didn't have any double locks before. I had only the LightDM lock screen, but now the old Gnome screensaver-like lock screen appears as well, just before the LightDM lock. The funny thing is that the old-style lock still appears even if I uncheck both System settings / Brightness and lock / Require my password when waking from suspend and System settings / Privacy / Security / Require my password when: Waking from suspend.
Since I upgraded to Vivid I get exactly the same issue Nils mentioned here: https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/1296270/ comments/ 25 and I didn't have any double locks before. I had only the LightDM lock screen, but now the old Gnome screensaver-like lock screen appears as well, just before the LightDM lock. The funny thing is that the old-style lock still appears even if I uncheck both System settings / Brightness and lock / Require my password when waking from suspend and System settings / Privacy / Security / Require my password when: Waking from suspend.