Possibly because it's duplicated content. They were both posted about the same time, so it's arbitrary which gets voted up and which gets voted down. But ideall

Possibly because it's duplicated content. They were both posted about the same time, so it's arbitrary which gets voted up and which gets voted down. But ideally only one would exist; voting one into oblivion is the easiest way to approximate that situation. I'm just speculating though.