Double lock screen Ubuntu 14.04

Solution 1:

Your question may have been answered here: The screen locks as soon as I close the lid of my laptop

In this response, Cornelius advises: Go to Gnome Control Center --> Brightness and Lock and turn off Lock and uncheck require my password.

You probably want to leave "require my password" checked for your purposes, but this may help you with your issue.

Solution 2:

There is a bug that is known in Ubuntu. More information about the bug can be found here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1296270

In version 16.04 LTS, the solution for me was to uninstall with sudo apt remove gnome-screensaver