1. An apparatus for detection of duplicate bug reports comprising: a memory; a matrix generator module configured to: receive a set of validated duplicate bug reports, identify pairs of keywords from the set of validated duplicate bug reports, wherein the pairs of keywords are from pairs of validated duplicate bug reports sharing an underlying cause but identified as dissimilar, having no similarity in keywords of their respective bug reports, calculate a co-occurrence score for the pairs of keywords from the dissimilar validated duplicate bug reports, and build a word matrix from the identified pairs of keywords and the calculated co-occurrence scores; a receiver module configured to receive an input bug report and the word matrix stored in one or more non-transitory computer-readable media, wherein the word matrix comprises a vocabulary of dissimilar duplicate words, and the dissimilar duplicate words comprise the pairs of keywords, wherein a first keyword of a given pair of keywords is a keyword of a first bug report and a second keyword of the given pair of keywords is a keyword of a second bug report and is dissimilar to the first keyword, further wherein the first bug report and the second bug report are dissimilar validated duplicate bug reports; an extractor module to extract at least one input keyword from the input bug report; a comparator module configured to compare the at least one input keyword with the word matrix to identify input dissimilar duplicate words corresponding to the at least one input keyword; and a searcher module configured to search a bug report repository with the identified input dissimilar duplicate words for detecting dissimilar duplicate bug reports.