Is it proper to save a copy checkbox?

[Koya]

Hi all,

I have a web form that I made sometime ago with two sections for addresses. Now, for section 2 I have a checkbox that says: "Same address as section1" and when the user checks it off then it copies the fields from section 1 to section 2. Now the form can be modified at a later time. If the user decide to check the checkbox, should the check mark be saved or not? Meaning if the user goes back to the form should the checkbox still be checked?

I know this is probably a design decision but wondering if anyone has ever seen it done before?

Also, why is it usually a checkbox and not a button since it really acts as a copy button?

Thanks.