What do you mean? Can you explain? You only get credit for the federal withholding in box 2. You don't get boxes 4 & 6 back. State withholding is in box 17.
The withholding in box 2 is not the actual tax. You are taxed on your total income. And the more total income you make you pay a higher percent for tax.
That is common. It just looks that way because you put them in as separate W2s and saw the tax due change in between them. If it was all on one W2 you would get the same result. And each job was withholding like it was your only job.
