It will only be .bak if you press enter. you can change it. But if you want to automate it you can do it with script.
The easiest script would be to call Ctrl+C followed by Ctrl+V
( The ID command is found in Keyboard customization dialog )
Command Type : MultiScript
// Run Edit->Copy
MC.RunCmd ID=Core.1311
// Run Edit->Paste
MC.RunCmd ID=Core.1312