User blog comment:J1coupe/Naughty Bear vs. Freddy Fazbear. Epic Rap Battles of Video Games Season 7./@comment-5805740-20141101173728/@comment-5264252-20141101180917

138 is a clone of 137 that replaced him in Destroy All Humans 2 and onwards, so I can imagine 138 replacing 137 halfway through the battle. :P