Which Saint, known as the "Apostle of the Apostles," was credited for two epistles in the Bible? 
Authorship of the Petrine epistles:  Most scholars today conclude that Saint Peter was not the author of the two epistles that are attributed to him and that they were written by two different authors. Saint Peter: Saint Peter (Syriac/Aramaic: ܫܸܡܥܘܿܢ ܟܹ݁ܐܦ݂ܵܐ, "Shemayon Keppa", Hebrew: שמעון בר יונה‎ ‎ "Shim'on bar Yona" , Greek: Πέτρος  "Petros" , ; r. AD 30; d. between AD 64 and 68), also known as Simon Peter, Simeon, or Simōn ( ), according to the New Testament, was one of the Twelve Apostles of Jesus Christ, leaders of the early Christian Great Church.
Saint Peter