Most likely, you have two strings that are similar in how they display but are different in how they are encoded. The easiest way to get two such strings is by reading one from a file and the other from the filesystem, for example via readdir.

If you are certain that your file system stores filenames as UTF-8, you can Encode::decode the filenames. You should do likewise with the filenames read from your file or stored in your program code. That way, the filenames should be consistent.