I'm running 1.3.5 -- I can't upgrade yet because the site I've "inherited" has a lot of custom code / database changes that I need to wrap my head around before attempting an upgrade.
The problem I'm trying to solve is that of duplicate address book entries. If I select "change your address," the checkout_shipping_address page contains a form that has my current shipping information, and a list of other addresses with radio buttons. If I select one of the address with the radio button AND leave the current shipping information filled in, it duplicates the current information as a new address entry. If I clear it out and then use the radio button, the selected shipping address displays.
I've combed through the code and can't even find where this duplicate is being created. I know I just want the address form to be empty, but I'm afraid I'll mess with the regular shipping address form.