Duplicate files with multi rename tool

[schockocraft]

It would be neat if you could use the multi rename tool to generate the duplicate files' names when duplicating multiple files at once.

Right now the duplicate tool (cm_CopySamepanel) isn't really suited to duplicating multiple files, except for rare special cases - you can only rename each file separately or overwrite letters from the start of the file names. It would be great if it just had an additional "Pattern rename" button that would open the MRT.