Well that is easy!
Ok When you dominate someone it means you have killed them 4 times in a row.
Thus when you kamikaze someone with a nade, if yours goes off first, you kill them and yourself. Meaning no kill credit is given to the 'other party' simple because he has given 0 damage to you.
So repeating this would simply mean the same enemy you have killed, has not given you any damage, thus you can dominate someone. If he gets a kill credit on you, all bets are off.