If you have a rhinoplasty operation that turns out poorly, it is extremely unlikely that your surgeon will be able to make it right in a second operation.  If you did good research in selecting your doctor, and saw many excellent before and after pictures of his patients, your doctor may be able to perform your revision.

But the vast majority of poor results are created by surgeons who probably shouldn't be performing rhinoplasty, and a doctor like that wouldn't have anywhere near the specialized skill to perform the revision.  Think long and hard before having your doctor revise your nose.