Some of it depends on where you are.
In my part of the world (NW Iowa) I have never been asked for paperwork. Course I think I only changed supplier once. I think most suppliers will likely need to do a leak test before they fill but they do this free, so it is no biggy.
The only thing that suppliers balk about here is 100 lb cylinders. Nobody here will fill them no matter if they are new or not.