Various software features such as classes, methods, requirements, and tests often have similar functionality. This can lead to emergence of duplicates in their descriptive documentation. Uncontrolled duplicates created via copy/paste hinder the process of documentation maintenance. Therefore, the task of duplicate detection in software documentation is of importance. Solving it makes planned reuse possible, as well as creating and using templates for unification and automatic generation of documentation. In this paper, we present an interactive process for duplicate detection that involves the user in order to conduct meaningful search. It includes a new formal definition of a near duplicate, a pattern-based, and the proof of its completeness. Moreover, we demonstrate the results of experimenting on a collection of documents of several industrial projects.