Not importing 'duplicate' files

Trying to import a small group of .arw files (~100) and I had originally edited some of them in MacOS Pictures. When I want to edit a file, I like to make a copy of the original so that I can retain the original despite what I do with the edited file. Because of this, I have 15 that will not import, because the system thinks they are duplicates.

What do I need to do to get Lr to allow me to import those files. I am early enough in my process of using this system to do just about anything, including starting over.

Thanks in advance!!