Whenever a charge say $Q_1$ and $Q_2$ is given to identical conductors we have to assume that charge is given to their outer side and not inner side to calculate redistribution.
Why? I tried to find redistribution by not following above statement and it's true that I'm not able to get right answer but i just don't why?
Similar charges always want to get as far away from each other as possible, so they sit on the outer surface of the two conductors. Assuming both are positive it will look like this.
Say $Q_2$ is negative the respective charges will lie on the inner surfaces of the conductors as the two opposite charges attract each other. Like so,
These instances occur purely on the basics of laws of attraction and repulsion.