Contradiction with Matthew 27:44
This verse states that both thieves reviled Jesus, which contradicts the idea that one of them did not.
Matthew 27:44: The thieves also, which were crucified with him, cast the same in his teeth.
Contradiction with Mark 15:32
Both robbers are said to have insulted Jesus, differing from any implication that one was more sympathetic.
Mark 15:32: Let Christ the King of Israel descend now from the cross, that we may see and believe. And they that were crucified with him reviled him.