You can’t nest a form within form according to the HTML spec. That is why it does not work.
Additionally, that checkbox submission will not be captured in the Gravity Forms entry.
What are you trying to accomplish exactly? If you use two Gravity Forms Address fields in the form, the second field will have the option to use the values from their earlier field, without the need to use an HTML field with a checkbox.
I have a couple of other fields like: Name, Email, Phone, Company that I wanted to also have the option to duplicate to. If you have any other recommendations to handle these, let me know.
Gravity Forms Copy Cat is a great solution for copying details like this. You copy via a checkbox click or automatically as the data is entered into the source field.
While this seems like a cool plugin, I don’t see a reason to pay that much for this one feature.
I guess if Gravity Forms has the option to copy the entire address field to another on the same form… I would hope that the same feature could be re-used on different blocks pretty easily :).
Gravity Forms does not have the feature, but you could add something like it using JavaScript. Gravity Perks is the easiest way to do it, but if you have no need for any of the other perks, and don’t want to pay for this solution, you would have to create the functionality yourself.