Remove duplicate articles due to multiple authors

[ArtPoon]

• Some articles have two or more authors from the same faculty or department.
• This is causing columns representing the same document to appear more than once in the term-document matrix
• We should screen for this by removing duplicate columns (it is exceedingly unlikely that two documents will have exactly the same frequency distribution of words out of 10,000 words by chance)

[ArtPoon]

• I don't think this is really going to skew topicspace because the word vectors are really long (total number of documents)...