on gutsy for amd64 do: sudo dpkg -i --force-overwrite /var/cache/apt/archives/gimp_2.4.0~rc3-1ubuntu5_amd64.deb
then do: sudo apt-get upgrade
on gutsy for amd64 do: apt/archives/ gimp_2. 4.0~rc3- 1ubuntu5_ amd64.deb
sudo dpkg -i --force-overwrite /var/cache/
then do:
sudo apt-get upgrade