Is it possible to use one animation controller for multiple objects?

yes.

the controller can be used for multiple sprites but the animation it controls would be different say if you're choosing spiderman or iron man obviously the animation the controller calls would be different.

in your editor you would just add the component animator for each character and then drag the animation controller you want.

for me I do a different controller and animation. it's just uh easier on organization for the way my mind works. a lot of ppl think its too much to look at.