Unless I misunderstand your situation, you don't need to take any action. When you look on Form 1040, line 71, do you see a dollar figure?
This excess behaves as a "tax credit" so to speak. What should happen is that all the line between 64 and 73 are added together to give you your total payments. These include your W-2 Federal withholding, certain refundable credits and line 71, excess Social Security taken from more than one employer.
Your refund on line 75 is the difference between your total tax (line 63) and your total payments (line 74).
This means, if you have any entry on line 71, your refund is THAT much more than it would be without excess Social Security.
I believe you understand, it's a different story when there is an excess from the same employer.
Again, pardon if there's a misunderstanding. If you have additional questions or comments regarding this, please feel free to post in the comments for further clarification.
