Trying to replace micro-oven combo with double oven and junction box only has two black wires and a ground. The junction box is hooked to two 40 amp breakers with a single throw, I am confused with junction box on the wire being the same color? Any thought, thanks

Trying to replace micro-oven combo with double oven and junction box only has two black wires and a ground. The junction box is hooked to two 40 amp breakers with a single throw, I am confused with junction box on the wire being the same color? Any thought, thanks

What is the color of the wires that are connected to the breakers? If they are both black then you have a straight 240VAC. Have you measured any voltages?What does the new oven require? What are the colors in the J Box?