Since I upgraded to Oneiric apt-get seems to ignore my architecture and gets the sources for both, amd64 AND i386, files from the repositoreis. this leads to constant "duplicate source entries" errors.
What to do?
**EDIT: Information provided by dizzy
Here is the requested file (since I'm not allowed to post more than two URLs I've modified the URLs not to be recognized (to std url / http:// to ..):
deb *std url* oneiric main restricted deb *std url* oneiric-updates main restricted deb *std url* oneiric universe deb *std url* oneiric-updates universe deb *std url* oneiric multiverse deb *std url* oneiric-updates multiverse deb ..archive.canonical.com/ubuntu oneiric partner deb *std url* oneiric-security main restricted deb *std url* oneiric-security universe deb *std url* oneiric-security multiverse deb ..download.virtualbox.org/virtualbox/debian oneiric contrib # disabled on upgrade to oneiric deb ..extras.ubuntu.com/ubuntu oneiric main #Third party developers repository