This happened to me for 2024 tax year. We received a check in the mail from the US treasury on July 1st, 2024 with no explanation. It was for the exact amount we owed on our 2024 taxes.
I logged into the IRS' web portal and low and behold, it showed that I paid twice, once on the day I e-filed (February 12, 2024) and again on the day I had set it up to autopay (April 15th, 2024).
No idea how or why I paid on e-file day but will pay allot closer attention this year.
