I have seen a variety of ways to mount roof lights of different types including roof beacons. One company I have worked for have taken out one of their rotating beacons to fit, in the same mount with the same roof socket, a pair of work lamps that shine on the load bed and to the side of the offloading area.
Being able to just unconnected one lamp and fit another in under a minute is well worth it with these commercial vehicles and something I am intending doing myself too

Certainly makes it a professional looking install when you get it right!