Haven't tried this out, but here's some stuff on how to use formulas to flip the name order. Of course, this might not work out with middle names, Juniors, etc.
https://www.contextures.com/excelsplitnames.html

There is also a fuzzy match option to merge data in Excel's PowerQuery. I haven't used that yet, but here's a video that might help: https://www.youtube.com/watch?v=aOl944MvkFc

If I have time I'm going to watch that tomorrow and try it on some lists I have that present similar issues. I just haven't had to do it yet.

Ann