If I were to re-Queen my remaining hive and I for some reason could not find or see to original queen to kill her would 2 queens fight. What would happen?
No......the queens would not fight. One would not kill the other.
They would never have the chance. The bees would kill the new (introduced) queen the first moment they could, prior to getting her out of the queen cage if they can.
Now there are two queen systems and procedures for getting two queens to live in the same colony. But that is not requeening.
That's another story altogether.