Elixir snippet to find MP3 files with the same track number in their filenames

rm-duplicate-tracknr.exs

re = ~r/^.*([0-9][0-9]) .*$/U
files = Path.wildcard("**/*.mp3") |> Enum.filter(&Regex.match?(re, &1))

groups = files |>
    Enum.group_by(fn f ->
        d = Path.dirname(f)
        f = Path.basename(f)
        [_, n] = Regex.run(re, f)
        {d, n}
    end)

dupes = groups |> Enum.filter(fn {_, fs} ->
        length(fs) > 1
    end) |>
    Enum.reduce([], fn {_, fs}, acc ->
        acc ++ fs
    end)

dupes |> Enum.each(&File.rm/1)

Warning: it deletes all the files with duplicate names (it doesn't keep the "correct" one), no prompting. I assume that you've got a pristine directory of .flac files somewhere else that you can recreate the correct MP3 files from.