After you file

Well I have 2 w-2's, same type of company for the same amount of time working there and same pay. One W-2 has 3 numbers, which is what its supposed to have and the other only has 2 numbers and it doesn't make sense to me as to why I will only be getting back $27, it just doesn't seem right when every year I do my taxes and it has 3 number. (I'm a part time employee, and a student)