In the computer game "amoebax" (available in the Ubuntu package manager), the options menu won't let you select the same key for both players, although if you edit the configuration by yourself, then it is possible to do this. You can make both sides use the same controls, or make both sides use opposite controls (so one side left goes other one right), and you can play the two player game alone. Although the sequence of colours received by both players is the same, the ghost blocks will be different on each side, soon missynchronizing them, and making the game much more difficult. This will also result in different amount of time needed to drop the blocks (although you can try to resynchronize them), so eventually the colours will not be the same on each side either.