Files Automatically Renaming Themselves - Duplicate File Names

I have a new laptop, so unless this is some weird feature that's specific to the laptop, then I assume it's a Windows 10 settings issue because I've never encountered anything like this before. I downloaded several JPGs and PDFs from various emails and began to change the arbitrary "234809238ksdfjskdfjsdlkf" type filenames to specific things indicating what they are, and I got done and realized all the stuff I typed was gone and the JPGs had changed to "filename(1)", "filename(2)", "filename(3)" and the same with the PDFs.. and "filename" was the name I'd assigned to the first file of each file type. The subsequent names I'd chosen were entirely different and the files were all unrelated to one another.