The widespread usage of Long Short-Term Memory (LSTM) accelerators in time-series related applications necessitates using a protection mechanism against faults caused by wear-out and environmental effects. This paper proposes a Concurrent Error Detection (CED) scheme combining low overhead duplication and residue codes to detect faults in multiply and add stages of LSTM accelerators. For the multiply stage, the CED consists of a multiplier for every LSTM multiplier with a temporal selection of data. For the add stage, the CED adders are shared among the LSTM adders, thus spatial selection is performed. The experimental results show that the proposed method yields good detection probability with a lower area and power overhead in comparison with the traditional duplication techniques that indiscriminately duplicate all hardware structures all the time.