Formatting text causes duplicate text

I am working in InDesign CC 2019 and I'm working on a large document (just over 100 pages). I am almost finished with the project and am doing some final tweaking and proofing, but a new problem has arisen. When I go in and format text, for instance make something italic, whether it is with character styles or by changing in the character tab, the type selected plus more type surrounding it becomes duplicated. So the correct formatting is on top of the old formatting. This has happened in the past but would go away when I changed the view. This time it doesn't go away. I tried clearing InDesign cache but that didn't correct the problem. Any ideas about what I should do? I'm working under a deadline!! Yikes!

My image below shows the type that has been reformatted to be in italics and is showing as a duplicate.

Thanks,

Linda