you can do what Gnu_Linux said. But doing this, you will remove/install two IC´s every time.
Alternatively you can remove only the IC of the good board, and connect only tx/tx, rx/rx and gnd/gnd (without gnd it will not work) of both boards, and program the bad board using the "brainless" good board. Of course, the USB connection is only connected from the good board to the computer.