Models are core artefacts in software development and maintenance. Consequently, quality of models, especially maintainability and extensibility, becomes a big concern for most non-trivial applications. For some reasons, software models usually contain some duplications. These duplications had better be detected and removed because the duplications may reduce maintainability, extensibility and reusability of models. As an initial attempt to address the issue, the author propose an approach in this study to detecting duplications in sequence diagrams. With special preprocessing, the author convert 2-dimensional (2-D) sequence diagrams into an 1-D array. Then the author construct a suffix tree for the array. With the suffix tree, duplications...