That's tough to answer I've made revisions to other surgeons' rhinoplasty work when it was the third or fourth surgery. However, these were somewhat limited or small changes and you have to understand that with each rhinoplasty procedure there is more scar tissue and things become a little less predictable as far as outcome is concerned.
Two is fine. A third procedure can be done but you want to be focused on your goal and have reasonable expectations. Gerenally speeking it is medically safe if that is your concern.
Hope that helps.