You will get duplicates. I reworded and updated lots of entries to make info easier to understand. I am currently working on another update with more new stuff. Just waiting to hear back from a few vendors with some specs I need. If you have lots of custom stuff you can manually reinput them or if you have a prog that will open an excel file you can copy and paste them.
The Data files are excel data files, if you have excel just double click on one of them. They are in your Rocksim9/data folder. If your system asks what to open it with use excel. With a Mac I'm not sure if Microsoft has a mac version of excel. After thinking about the copy and paste process, if you have only a few custom files it would probably be easier to write the info down and add it manually. Because if you are not familiar with renaming files it gets confusing. With excel you can't open two files with the same name at the same time.