ONLY hazelnuts, as far as I'm aware-- and Nutella is huge, huge, huge business-- so it's really unlikely that there is anything else in there.
Also-- filbert orchards don't tend to co-locate with any other kind of treenut. The only other tree nuts that will even grow in the same climate are almonds (badly-- not, not, not commercially), and walnuts (which are harvested completely differently).