All Q400s have this, in fact, all DHC-8 variants have this, IIRC. There is one red beacon on top of the fuse on the Q400, and on top of the vertical on all other models (I am not sure about the -300, as I have not worked on one). On the -200, it is referred to as a ramp beacon, and the flightcrews will from it to the strobes when taking the active runway, or when departing the runway. Same thing on the Q400, the lights are just in different places.
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