A system for confirming the detection of a fire using a plurality of radiation or flame sensors each equipped with a radiation detector and an optical filter having a spectral transmission characteristic in which at least one optical filter is redundant to at least one other optical filter. The result is a system having operationally redundant sensors. In use, if a fire is detected by one of the redundant sensors without including the other redundant radiation sensor in the fire detection calculation, then a fire detection algorithm can switch to the other operationally redundant sensor to check for confirmation of a fire. Due to the spatial separation and if the object is small and close, a different result will be obtained with the redundant detector being used in the calculation compared to the primary detector that is associated with the redundant detector.