The twinner is a tool which makes it easy to create a tiddler in your home tank with the same name as the one you are currently reading.
Your home tank is the tank named after your username.
The interface is only presented when you are logged in and not in your home tank.
When clicked, an interface will be revealed presenting a textarea and a tag interface. If the target tiddler already exists, its text and tags will be shown available for editing. Otherwise the textarea shows a link back to the current tiddler and the tags are configured to notify the modifier of the current tiddler that you have made a twin.
When confirm is clicked, the tiddler is saved and you will be redirected there.