Can a 1 switch function for two different lights?

It would probably be easiest to use two switches, however one could use a what is called a "double throw" switch if the wiring is accessible enough to make the connections . You would probably want a three position, center off toggle switch, or a rotary switch with an off position. Such a switch should be available as a lamp replacement part. You might even find from a lamp parts supplier, a switch that will switch in the sequence: off : a : b : a+b