Connect two 2-pole breakers together?

Twin breakers two breakers in one slot Tandem breakers are only allowed in number and slots that they are aproved for Most 40 slot panels are only approved for 40 poles I am looking two breakers in one slot Physical Appearance: These breakers are larger than single-pole breakers and occupy two slots in the electrical panel They have two handles

two slot A tandem breaker is designed to allow two 120-volt circuits to be fit into a single slot in the circuit breaker box They are normally