Find and replace duplicates in Array, but replace each nth instance with a different string

Question

I have an array below which consists of repeated strings. I want to find and replace those strings, but each time a match is made I want to change the value of the replace strin

Answer 1

EDIT

Counter and than sorting is simpler:

L = ['champ', 'king', 'king', 'mak', 'mak', 'mak']
counts = Counter(L)
res = []
for word in sorted(counts.keys()):
    if counts[word] == 1:
        res.append(word)
    else:
        res.extend(['{}{}'.format(word, index) for index in 
                   range(1, counts[word] + 1)])

So this

['champ', 'mak', 'king', 'king', 'mak', 'mak']

also gives:

['champ', 'king1', 'king2', 'mak1', 'mak2', 'mak3']