Renaming files appends a `_1` at the end of each one

[HitLuca]

I'm not sure why, but when renaming files with perfectly fine filenames (TEST.TTF into test.ttf) produces correct results if it wasn't for a _1 appended after each filename (test_1.ttf).

[JannisX11]

That seems to be because it's checking if there is already a file with the new name to avoid overwriting, and that check is case-insensitive.
This would be fixable though by checking if it's the same name, just in a different case.

[HitLuca]

I find myself editing filenames to uppercase/lowercase often, so this change would at least to me be quite nice. For now what works is doing it in two steps, first do what I need and then re-batch rename to remove the _1