It's not outdated in regard to the question.
The duplicate columns should not be there. They should be removed from the package.
The reason for the restriction is that the input and output views will return two columns...
select ... content_revision.title ... yourtable.title ...
the second one will "win".
and also this would break anything which, say, lists cr content for a package using the base type's "title" attribute.
Packages shouldn't break other packages or utilities that use the object datamodel correctly ...
