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As long as the mistake doesn't result in any additional taxes (or refund for you) - the IRS will not likely raise the concern.
You may contact the IRS by sending a note - if you want so - but I would not do anything unless the IRS sent the note to you. If they do - you should be prepared to explain - while very unlikely - it is still possible.
Again - as long as there will not be any difference in tax calculation - it is unlikely you will get anything from the IRS.