I was under the impression that having Ad Groups in different campaigns targetting the same keywords would run the risk of a no-no that is displaying 2 ads in the same SERP. I thought the only proper way to have mutually exclusive ads targetting the same keywords was to have them under one campaign, in seperate ad groups and to turn on optimization.
Unless Google introduces some bug, there is no way to get two ads displayed at once from one account. All ads are in Google searches no matter what, but if a keyword is in multiple places, only one will be displayed. The one chosen is based on the one Google thinks it will get the most money from based on CTR and bid. Do a search on this forum for the exact method used that AWA posted a while ago.