All Ubuntu 14.04 machines are visible via Bluetooth as 'ubuntu-0'. This cannot be changed; there is simply no GUI option to do so. This is a regression. I do not remember how it worked before in 12.04 but I believe that the hostname was used.
Thus to pair a device, be sure not to have more than one Ubuntu desktop visible or else you will have a hard time figuring out which machine you are trying to pair with.