Given that there is a large number of questions on Stack Overflow related to Drupal, could we pull some of the good ones over to Drupal Answers? Otherwise, you're going down that redundancy path, anyways.
Moderators on Stack Overflow do have the ability to migrate questions to any site; flag the question for moderation attention, and they will migrate it, if they think it is worth doing it.
Keep in mind that:
- Moderators don't generally migrate the question if the migration is not asked from the user who asked the question
- The migration is preferably done when the user who asked the question is also active in the site receiving the question, otherwise migrating the question would mean to make it abandoned
- There is another site accepting this question is generally not the reason why the questions are migrated
- Old questions are not normally migrated and now Community Moderators cannot even migrate too old questions
- The general rule is not to migrate questions that are on-topic in the site where the question has been asked
If you have any reason to see the question migrated, and you didn't ask the question, explain in the flagging reason why you think it is better to migrate the question. If you convince the moderators, they will migrate the question.