For example, one of the earliest versions of Mark ends with the death of Jesus, while later versions tack on a resurrection story.
However, this dating is uncertain since it is based on handwriting analysis.
Even if the date is correct, we aren't even completely sure the text really is from the Gospel of John since we only have five complete words and nine partial words on one side and six complete words and seven partial words on the other.
This fragment could just as easily belong to the Gospel of Nicodemus or another text entirely.
Eusebius Pamphilus of Caesarea rewrote his History of the Church at least five times to conform to the changing doctrine of the time.
Eusebius obviously had no problem with rewriting history.