by p. 186 of the core rule book, a warlord trait is "a preffered tactic or personal ability that marks them out amongst their peers." By that statement, I don't think you can grant the same trait to multiple characters. That said, you normally don't get more than 1 warlord trait for an army. In addition there is nothing that explicitly denies you from having 2+ characters with the same trait (with regard to this stratagem), but again you don't normally get more than 1 warlord.
"The law of very large numbers: Given enough attempts, anything can happen."
"If brute force isn't working, your'e not using enough of it."