Repair probably depends on how the keyboard is built. The water could have caused the general gunk in and under the keys to cause stickness so pressing one key "drags down" another.
Or the water created shorts that make the input appear as if both keys are now being pressed.
Search your laptops make and model along with the words like "keyboard", "clean", "repair". Might come across some DIY fixes especially if your laptop is prone to such problems.
Or at least a better idea of how serious the problem could be.