What do you mean by "real names"? Peter's name in Aramaic is rendered as כֵּיפָא (Kepha), in Greek as Πέτρος (Petros), in Latin as Petrus, etc (all having the rough meaning of "rock" or perhaps "jewel"). Ignoring translation, his original name was said to have been Simon/Simeon, until Jesus gave him the name Peter (Mark 3:16, etc)

Some of the names differ between the Gospels, too. One is identified as Thaddaeus in Matthew, but as Judas ( "not Iscariot") in John, and as Jude in Luke. Bartholomew is identified as Bartholemew in every gospel except John, where he is Nathanael.

This isn't even to get into the debate about the historicity of the disciples themselves.