Well, first off I don't think you'll really have anything to worry about with these guys as far as someone getting hurt. There is really no combat involved. If you place one male in a tank with your female, most of the time he will just inspect the place and find a nice spot to sit around. Occasionally, he will actually tounge flick the female and go ahead with breeding, but not usually. After placing one in, go ahead and place in the second male. Usually it is just a matter of time before they are both actively courting her. One will usually dominate her more than the other and so he kinda wins out. You will still leave both males in with the female as sometimes they will both breed her and this improves your chances. Leave them in there untill all breeding ceases. You might think that a month or so is plenty of time, but this is not the case. It will take a while of breeding before you notice the female actually lifting her tail and inviting the mating, it is around this time that she has been turned on enough to ovulate. They tend to know when enough is enough and will stop on thier on. Once this happens, go ahead and seperate the males from the female. Good luck!