the problem would be the attenuation and the cable connecting the two GPS. I imagine you could splice the cable, however you could get a low loss splitter which would give you two outputs from one input. I assume both the GPS are the same as some antennas have an amplifier and filters in the antenna housing itself which might not be compatible with a different make/model of GPS receiver.
I'd be interested in your results if you try it. (I would think a TV cable splitter would work, assuming the connectors the compatible with the GPS cable)
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