This paper explores a new dependable real-time task execution scheme for a many-core system. This scheme is based on duplication with temporary TMR and reconfiguration. Unlike a common scheme with several spare units, every processor core in our scheme is used for task execution. Thus, redundant processor cores contribute to both the reliability and performance of the entire system. We first show the implementation details of our scheme. Then the proposed scheme is analytically evaluated using abstracted models and compared with two other schemes.