Do you submit your unique website's content to article directories?

Do you re-use your website's contents by submitting them to article directories AFTER they're indexed? Will this hurt your position in SERPs in any way? I saw this in a book, but am quite doubtful about it, duplicate content is bad.
What do you do?

Also, do you submit the same article to all directories once? I heard submitting one unique article only to one directory instead of all gives better results.

personally i do but i make sure the article is spun. In theory G should be able to identify the original content from the dupes

I see. What about article submission? Same article, multiple directories or one article per directory? I know it can be quite costly if you do the latter but..

personally i do but i make sure the article is spun. In theory G should be able to identify the original content from the dupes