Double Tapped Circuit Breaker
Tom O'Dwyer
Here's an example of a double tapped circuit breaker;
Double tapping is when two hot wires are squeezed into a single circuit breaker. Typical breakers aren't designed for two wires, the connections can loosen and the current can jump between wires causing excessive heat and microarcing. This is a dangerous scenario which can become a home fire hazard. Recommend evaluation by a licensed electrician.