I wonder what would happen to “sending two, returning one” under the rule I suggested here which you might call delayed-capture go or sanitary go.
After 2, the captured black stones stay on the board until Black’s turn:
So Black needs to play a ko threat elsewhere (3, 4) and remove his stones before returning to capture:
White can play elsewhere or just pass, removing the stone at A1, and we return to the original corner position. White has lost nothing while Black wasted a ko threat, right?