MeNpHiS,

You can use either repository.maemo.org or skeiron.org (the mirror) as the former has come back up but is extremely slow.

I would suggest you disable either of them instead of keeping both of them and running into what you got.

After disabling do an apt-get update and as you can see skeiron.org for Extras you have double-entries so you may want to delete one of them if you use skeiron.org in place of repo.maemo.org for the time-being...