Oops! . . . I changed it again

Abstract

Duplicated passages of source code-clones-are a threat to software maintenance as modifying duplicated code causes additional change effort and bears the risk of incomplete propagation of changes to all copies. Although previous studies have investigated the consistency and threats of changing clones, changes have always been analyzed detached from another-not considering that individual clones may change more than once during their lifetime. In this paper we present our study on the patterns of consecutive changes to clones in real systems and discuss in how far they are suitable for identifying unwanted inconsistencies.