Which general researc topic this paper belongs to? This paper studies the variation of error detection by duplicate instructions (EDDI) runtime performance overhead and characterizes the root causes. The paper reports that five instruction factors and one cache/memory factor contribute to the variation of program EDDI performance overhead (RPO). Based on the empirical findings, the paper proposes FuzzyB and Celer to identify the upper bound of EDDI RPO across the search space of program inputs and accelerate the EDDI RPO, respectively.