yes, common to do this, but there is most often a 'drop charge', so they can relocate the car back to original departure point. (tho they seldom actually do this). It is good to check around, as some drop fees are quite high to avoid all the cars ending up in one location.
Thus it can be cheaper to drive the opposite direction you previously planned, if the car company has too many cars at your arrival destination, and too few at your deprature point. (you get to relocate their car for them, and you pay for that privilege (there will still be a 'drop charge'...

... nice guys!!)