This script returns a list of files that are duplicated within your Git repository.
Usage: python "DuplicateGitFilesChecker.py" "<git_repo_path>"
If you need this script to work with folders as well, please create an issue in the repository.
I have a working method for handling folders by iterating recursively through the directory structure using the following Git command:
git ls-tree --name-only -d HEAD
I didn't code this because I personally don't need it, but it effectively lists directories in a Git repository, which would be a starting point to implement the script to works with folders as well.
Something else useful is the git command:
git config core.ignorecase true (can be set to true, false or unset)
see more at: https://git-scm.com/docs/git-config