Double car insurance ? Is he right?

Hi ladies I need some help, so my husband purchased an used car from a dealership yesterday, when he came home he said that we’re paying (monthly)120 for some sort pf insurance and 450 on the car... and i was like ok that’s good but then he mentioned that he had to call our previous insurance to add the car so I was very confused cause it seems like we will have to pay doble insurance? Which makes no sense to me, let me tell you he is impulsive and is hard for him to focus and pay attention to a lot of details so he can’t tell me exactly what they told him about that... I’m relatively new to USA and i had never purchased a car, we got our previous at from somebody on Facebook and we payed cash so totally different experience...

So do we have to get our own insurance on top of the one we’re paying to the dealership?

Thank you I’m advance