Comment 2 for bug 304417

This error has also been seen by me. I have just done a clean install of Jaunty Alpha2 64 bit (which comes with kernel 2.6.27-7!) I then did a system update via the update icon that was displayed (in top righthand corner of desktop) and it updated the kernel to 2.6.27-9. Software sources for Alpha2 are still using Intrepid, but that's another problem). I modified the software sources for Jaunty as per the Ubuntu forums and performed an sudo apt-get update via terminal and this was where I got the error:
Preparing to replace libgnome2-0 2.24.1-0ubuntu4 (using .../libgnome2-0_2.24.1-1ubuntu1_amd64.deb) ...

Unpacking replacement libgnome2-0 ...

dpkg: error processing /var/cache/apt/archives/libgnome2-0_2.24.1-1ubuntu1_amd64.deb (--unpack):

 trying to overwrite `/usr/share/man/man1/gnome-open.1.gz', which is also in package libgnome2-common