There's no way to do that.
You can change the colours, whether/when hot-paths are enabled, and turn off some of the buttons but you can't swap the path and buttons around.
Opus has a Duplicate command which, if you're using the default toolbars, is the right-click action of the Rename button.
When you run the Duplicate command you'll see a dialog with the old and new filename. If you type over the new filename then what you enter will be used for just the first file that is being duplicated; however, you can also type a wildcard into the old name, and a different wildcard into the new name, to tell Opus how to name all of the files being duplicated. For example:
Old Name: .
New Name _copy.
would Duplicate these files
Blah.txt
Moo.jpg
Zuma.png
to these new files
Blah_copy.txt
Moo_copy.jpg
Zuma_copy.png
If you want a button that you can press to duplicate the selected files in a particular way without any prompts or typing then you can sort-of do that now, although there's a restriction that means the new names can only add text to the start of end of the filename. (I noticed this recently and have filed a feature request asking for it to be made more flexible.)
You can make a button which runs this command
Copy DUPLICATE AS *_copy
and it will duplicate the files by appending "_copy" to their names. Unfortunately that will mess up their extensions, but if you just want a way to quickly create a backup file then it does a good job. If you do want to duplicate to create backups then even better, perhaps, is to include the current date in the new name, like this:
Copy DUPLICATE AS *backup{date|yyyy-MM-dd}
This shouldn't happen but does sometimes. Have a look at this FAQ to troubleshoot the problem and let us know if you find anything: