It's Supernatural Season Two, Episode Five, and it is mostly about the demon babies. Liz explores the question "Can twins be trusted?" when she goes into the True Crime tale behind Spahlaski twins. The brothers who commit crime together, end up in prison together. And lest we forget - Dr Bad Ass is In!

Sources:

• https://murderpedia.org/male.S/s/spahalski-robert.htm
• https://www.oxygen.com/killer-siblings/crime-news/twin-killers-robert-stephen-spahalski-attica-michael-benson
• https://medium.com/true-crime-addiction/identical-twins-connected-by-dna-and-murder-true-crime-6e22df2b84e5
• http://maamodt.asp.radford.edu/Psyc%20405/serial%20killers/Spahalski,%20Robert.pdf
• Killer Twins Benson, Michael. 2010. 
• Democrat and Chronicle (Rochester, New York)13 Jan 2010, Wed. Page 11. 
• Star-Gazette (Elmira, New York) March 12, 2010 Friday By Jason Whong
• http://www.supernaturalwiki.com/Ben_Edlund
• http://www.supernaturalwiki.com/2.05_Simon_Said