Can we do Istikhara twice for something?

Based on my researches, in the Urf (custom or tradition of the society), Istikhara often/always is done once for everything. Some days ago, a friend of mine did a Istikhara for doing something (to take trip to a specific country), and the result of Istikhara was bad/negative for his travel. Some days later -- after his negative Istikhara -- he decided to do another Istikhara (in order to have [perhaps] a positive result of Istikhara to allow him to take trip!). It seems he insist on this travel and as if he want to do his another chance by Istikhara (!) to take the consent of Allah for travelling! But, my 2 questions are: **Is it permissible/halal to do a/the second Istikhara in sth whose first result of Istikhara was negative? (In order to get a positive result?)** **What will happen if somebody do against Istikhata's result?** ---- **Note**: Both Shia and Sunni viewpoint would be appreciated.