After looking at the image you posted I am left in no doubt about why you have a spare motherboard.
For whatever reasons your keyboard has been cobbled together from at least two different keyboards.
This would explain why you have discoloured keys, as they are likely to be from different keyboards. With one of the keyboards being subjected to cleaning with an incompatible cleaning product or has been left uncovered in bright light conditions.
For whatever reasons your keyboard has been cobbled together from at least two different keyboards.
This would explain why you have discoloured keys, as they are likely to be from different keyboards. With one of the keyboards being subjected to cleaning with an incompatible cleaning product or has been left uncovered in bright light conditions.