The force of attraction between two bodies of masses m, and m_{2} and separated by distance r is given by Newton’s universal law of gravitation .
(where M = Mass of the earth, Ft = Radius of the earth)
And from the equation it is clear that, acceleration due to gravity (i.e., g) depends only on mass of the earth, the radius of the earth. So, two bricks tied together will not fall faster than a single bricks under the action of gravity. Hence, the hypothesis is not correct.