This is a dual event die clash that is found on a 1956P Lincoln cent.

While not that evident, two sets of clash marks can be seen on the obverse die. The partial N from cent can be seen at Lincoln’s throat, while the top of the letter E can be seen clashed just before the 1 digit in the date.

The reverse die shows a faint clash mark from the right side of the N in CENT, up to the bottom of the E in ONE.