Have "Copy Duplicate" a default variable?

When I duplicate a file with Copy Duplicate, the new name of duplicated file is saved in a variable? If yes, what is the variable name?

Thanks beforehand.

It isn't. The only thing that sets a variable like that at the moment is the Filetype NEW command. (And the @set command, obviously.)

Do you know any way I can select new duplicated file automatically?

Regards

Not in general.

You could make a button which asks you what text you want to prefix/insert/append to the filename which stores that in a variable and then runs the duplicate and select commands using the variable. That would only work for certain types of duplications and it might be tricky to avoid selecting existing files that match the pattern.