Hi,
It's not just about copying the files. You will need to edit them and change everywhere in them the name of the plugin with the new name of the plugin. Without PHP knowledge, that's not possible.
As Xavier suggested, you can use the check payment method which roughly the same are the western union/bank transfer plugin. You just have to change its name and potentially its translation keys. You can also use the collect on delivery payment method in order to achieve the same display as bank transfer ans western union plugins. That way, you have your four payment plugins, and you don't have to write any code.