would len(good_guesses)==len(list(secret_word)), if the secret word has 2 of the same letter?

Hey guys, I've watched this video several times to see what i may have missed something but I just don't see it.

My main problem is if the secret_word has 2 of the same letter ex "sparta",

The loop would only append the letter once even though it turns the underscores into its corresponding letters. And if you were to type in the letter twice the loop responds that you have already typed in the letter.

elif guess in good_guess or guess in bad_guesses:
    print("You already guessed this letter.")

if guess in secret_word:
good_guesses.append(guess)
    if len(good_guesses)==len(list(secret_word)):
        print("correct! The secret word it {}."format(secret_word))
        break
    else:
        bad_guesses.append(guess)

if secret_word=sparta when the user guesses 'a', good_guess=[] gets "a" only once , and can't get another one so the len(good_guesses) will never equal len(list(secret_word))

Is there something else I'm missing?