I just tried using the mod by itself and had no issues at all.
After that, I tried to recreate your issue. I tried using my bugfix and got different errors. So I tried deleting the backup folder between the first and second "apply" of only this mod, since that would result in applying this mod on top of itself, and got exactly the same issue. The key is the the mod is not actually attempting to add itself twice to the game, but use itself as a temporary change to the mod system to install itself properly.
In the case that you did not delete the backup folder manually, check the games error terminal to see if your game is creating a backup every time it runs. If so, then I recommend using my current bugfix on Strive's Discord(channel #mods) to diagnose the location of the issue. Though the current bugfix cannot be used with this mod.