There's a debate opening up right now on whether or not we should eat clones vegetables, fruits, or animals. A lot of people are resisting this based on false assumptions that these foods would be dangerous for you, where that's really not the case. Cloned food is pretty much our only option if we're going to sustain 9 billion people or more.
But the earth WILL reach a population cap eventually, where she simply cannot sustain any more human beings. By this point however, we should probably be advanced enough to terraform and colonize other planets. So really, there's not much reason to worry.