You can only assign one bind command per entity at a time, but you can change it during the game using script commands. Some time ago there was a discussion about changing the bind without a script, but I don't think anyone found a way to do that.
Say you have a light called "L1" and two func_rotate(s) called "FR1" and "FR2" and say at level start you bound L1 to FR1 using the k/v pair on L1: bind/FR1. Then in your script you would put these two lines:
Trigger that script anyway you want then L1 will become bound to FR2.
And while you can't bind one thing to more than one thing, you can set up a hierarchy, that is bind L1 to FR1 then bind FR1 to FR2. By using this hierarchy (just like most 3-D modeling programs do) is how you create complex machines. I'm not saying that particular combination is helpful, however, it gives you an idea of the possibilities.
It's good that you've discovered how to open the ID maps and while at first they seem confusing and disconcerting, once you learn how to pick them apart, you can always use them as reference to see how various things were accomplished. Use the "view" feature in the menu to strip away layers, for instance unticking the "path" will hide the path lines, and make the map easier to examine. Untick the "triggers" and "clip brushes" and that really helps a lot to make the maps more easier to look at.