With model-based development becoming an increasingly common development methodology in embedded systems engineering, models have become an important asset of the the software development process. Therefore, techniques for the automatic detection of clones in those models have been developed to improve their maintainability. As these approaches currently only consider syntactic clones, the detection of clones is limited to syntactically equivalent copies. Using the concept of normal forms, these approaches can be extended to also cover semantic clones with identical behavior but different structure. The submission presents a generalized concept of clones for Simulink models, describes a pattern-based normal-form approach, and discusses results of the application of an implementation of this approach.