If you mean RPG_RT.exe and RPG_RT_original.exe, the former has the default icon changed, while the latter is simply a backup generated in case the executable is corrupted.
You can’t ship “two language versions” of the same game in the same folder, because their files would share filenames, which means the maps would contain either the original or the translated text. You could certainly edit the game and add both scripts plus a flag for the language, but that goes way beyond the scope of a translation.