Cloning in source code is a well known quality defect
that negatively affects software maintenance. In contrast,
little is known about cloning in requirements specifications.
We present a study on cloning in 11 real-world requirements
specifications comprising 2,500 pages. For specification
clone detection, an existing code clone detection
tool is adapted and its precision analyzed. The study shows
that a considerable amount of cloning exists, although the
large variation between specifications suggests that some
authors manage to avoid cloning. Examples of frequent
types of clones are given and the negative consequences of
cloning, particulary the obliteration of commonalities and
variations, are discussed.