  Code comments are the primary means to document implementation and facilitate
program comprehension. Thus, their quality should be a primary concern to
improve program maintenance. While much effort has been dedicated to detecting
bad smells, such as clones in code, little work has focused on comments. In
this paper we present our solution to detect clones in comments that developers
should fix. RepliComment can automatically analyze Java projects and report
instances of copy-and-paste errors in comments, and can point developers to
which comments should be fixed. Moreover, it can report when clones are signs
of poorly written comments. Developers should fix these instances too in order
to improve the quality of the code documentation. Our evaluation of 10
well-known open source Java projects identified over 11K instances of comment
clones, and over 1,300 of them are potentially critical. We improve on our own
previous work, which could only find 36 issues in the same dataset. Our manual
inspection of 412 issues reported by RepliComment reveals that it achieves a
precision of 79% in reporting critical comment clones. The manual inspection of
200 additional comment clones that RepliComment filters out as being
legitimate, could not evince any false negative.
