Convert File Extensions/type .pptx to ppsx

I have been tasked to add a workflow to a our presentation repository. When a file is uploaded to the repository, they want that file converted to Presentation Show. When a file is uploaded in .pptx format it should be converted to .ppsx format so that there are two files. We currently use the workflow for the PDF, JPG, HTML conversion file type, but is there a way to have filetype.pptx and filetype.ppsx? Currently this is a manual step we are trying to automate.