Cleopas in Luke 24 and Clopas in John 19 — the same person as a named eyewitness source

Luke 24:18 names Cleopas (one of two disciples on the road to Emmaus after the resurrection). His companion is unnamed. John 19:25 names "Mary the wife of Clopas" at the cross. Clopas is a rare Semitic form of the Greek name Cleopas — the two names almost certainly refer to the same person. Both Luke and John reference this person at events where the main disciples are absent. According to Hegesippus, Clopas was the brother of Joseph (Jesus's father) and father of Simeon who succeeded James as leader of the Jerusalem church. Cleopas/Clopas was thus a living, prominent eyewitness.