I’m not sure that I have understood your question but I think that your goal is to duplicated from one file document to other.
1º – To do this you need to download the Community Commons.
2º – On the toolbox, you have access to some java actions. One of them is called Duplicate file document, you can use it by just filling 2 inputs (File to clone and clone target)
I hope it helps! Best Regards,
Have a look here: https://docs.mendix.com/appstore/modules/community-commons-function-library/#33-files
There are several java actions available in the community commons module.