Atualização via update-manager -d de 12.04 para 14.04

[Jose Henrique A Gomes]

duplicidade no sources.list

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.13
ProcVersionSignature: Ubuntu 3.5.0-52.78~precise1-generic 3.5.7.33
Uname: Linux 3.5.0-52-generic i686
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: i386
Date: Thu Jul 3 08:56:38 2014
GsettingsChanges: com.ubuntu.update-manager launch-time 1404388464
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release i386 (20130213)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=pt_BR:pt:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=pt_BR.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2014-07-03 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2014-07-03 08:54:59.736997
 Log time: 2014-07-03 08:55:13.827402
 Log time: 2014-07-03 08:56:02.556828
 Log time: 2014-07-03 08:56:46.722553
VarLogDistupgradeTermlog: