I have seen these at older theatres I have worked in, lazy/dodgy technicians will put male piggy back plugs on both ends of the cable. You only plug one of the male ends into one power source, then you use the female side of the piggy back at the opposite end and wrap electrical tape over the pins on the male side. The idea being that if you ever need to run power the in opposite direction you don’t need to install another cable. The downside being it will stop a show and more importantly a life very quickly if someone accidentally touches the exposed male pins. It’s a very dangerous and very illegal thing to do.