If you have paid the balance due already then ignore the bill that came in late ... sometimes the department that sends the bill doesn't get the info that the bill was paid and the computer spits out an automated bill.
Here's the IRS's site that explains the CP14:
https://www.irs.gov/individuals/understanding-your-cp14-notice
You'll notice that under "What do you need to do" there's the point "Contact us if you disagree." That's about all you can really do here and they instruct you to "Call us at the toll free number on the top right corner of your notice. Please have your paperwork (such as cancelled checks, amended return, etc.) ready when you call." If the IRS has got something wrong here then you have to go to the time and effort to set them straight.
Or in your case, since you live out of the country where mail can take months to get to you, the bill was in the mail when you paid the balance due. Again you can ignore the notice if you know the amount was paid. If you sent a check make sure it was cashed and if you paid online at IRS,gov they you should have the receipt.
Thank you so much
to be specific,
I paid tax when I received first notice exactly I paid May 24th and
Second notice (Cp14) was issued on June 3 and due date was June 24, but this notice was delivered on July 2nd.
Also my School office person told me, (my tax was for my scholarship and fellowship) IRS often update late so, if you paid exactly same amount, you can ignore.
I hope you and my school office are right.
Anyway thank you so much!