Mark tells us that Jesus healed a blind man as he left Jericho. Mark 10:46 tells us who he was:
Luke 18:35 agrees with Mark that there was only one blind man:
However, in Matthew we have two blind men. This is Matthew 20:29-30:
It's open to you to say that Mark and Luke do not explicitly rule out the presence of the second one that Matthew mentioned. However, this would not be the only time this happens, and the more times you have to say it, the less plausible it becomes. Note that it always seems to be Matthew that's adding stuff. It's a habit of his.
Looking Unto Jesus claims that Matthew's gospel is more accurate, since Matthew was an apostle of Jesus and was actually present at the incident; however the mainstream view of academic Biblical scholarship is that the gospel of Matthew was not written by the apostle Matthew. Indeed, it's very well established that the author of Matthew used Mark as a source, which he wouldn't have had to do if he had actually been an eye-witness to the life of Jesus. If you want a convincing argument for the primacy of Mark, see Fatigue in the Synoptics, a serious work that far surpasses us amateurs.