This ensures that each twitter username is in the list only once.

Here is an example url where you could scrape more than one twitter url:
http://bradfrostweb.com/blog/post/death-to-bullshit-at-creative-mornings/

The above example link makes more sense once my no-title-links branch
is grokked. The no-title-links branch allows for searching all twitter.com urls 
or usernames if one can't be found with the appropriate title.