I noticed that renaming a recording from say Broken to BROKEN doesn't work probably because there's a .toLowerCase() check for the name string.
Current Replay Mod version for MC version 1.8.9

Cannot reproduce.

Works for me. Maybe you have to append append something to the start or end?

I don't get your reply. It does not in any way seem to relate to the initial issue description and I don't even see anything wrong with it.

I'm very sorry about that. That was the folder for another bug report. I'm very sorry for sending the wrong one. This is the right one. (Let's hope this goes right.)

Which operating system are you using? Could it be that it doesn't allow for two files with the same name but different capitalization?

Windows and that was the issue. Sorry about that.