Although it is possible to ignore the latter entity based on 'lex' attribute and its belonging sentence, this rule fails to deal with entity "c-jun gene" in the example of "c-fos and c-jun genes" as the 'lex' of "c-jun gene" is mistaken as "c-jun genes".
in this case, we ignored "c-fos transcript" and instead kept the "c-jun transcripts" as a flat entity.