Why do I have 2 coaxial cables?
If it looks anything like the one in this image, it is likely just for historical reasons. At least here in Belguim, they are pretty much always just wired in parallel internally. 

When everything worked with antennas, you would be able to use a different antenna (and perhaps cable, see note) for the FM radio band than the TV band. The connector for radio is different from that of TV, so you can't plug the TV into the radio cable and vice-versa (it wouldn't damage anything, just wouldn't work). Now this is pretty much always done over just one coaxial cable, and the same coaxial cable carries both FM radio and TV signals (sometimes also other things like phone signals and internet, through standards such as DOCSIS). To support the different applications they still have two connectors, but internally they connect to the same wire.



Image source (Niko Product page)

Note: They would use different cable not because one cable didn't work at both frequencies, but to avoid issues with power combiners.