your URL http://www.washingtonpost.com/posteverything/wp/2014/07/24/my-son-has-been-suspended-five-times-hes-3/?hpid=z1 The other URL http://www.washingtonpost.com/posteverything/wp/2014/07/24/my-son-has-been-suspended-five-times-hes-3/ Not exact match. That's my guess.
Yeah, I noticed those two things. I wasn't sure if it had to be an exact match or how exactly that notification gets triggered. The more you know.
The only part of the URL that the dupe filter should ignore is the anchor segment. Perhaps the protocol as well. Not sure if hubski can handle user/pass, I should try it...
Web servers will ignore unrecognized query arguments and often they are used for weird purposes that aren't user-visible. When I submit a link, I chop off the question mark and everything after, if the link still works that way. protocol://user:pass@example.com/path/to/file.txt?query=var&this=that&one=two#anchor