Why is create_row returning so many cards?

from cards import Card
import random

class Game:
    def __init__(self):
        self.size = 4
        self.card_options = ['to', 'yo', 'fi', 'fo', 
                         'mo', 'it', 'ab', 'ta']
        self.cards = []
        self.columns = ['A', 'B', 'C', 'D']
        self.locations = []
        for column in self.columns:
            for num in range(1, self.size + 1):
                self.locations.append(f'{num}{column}')

    def set_cards(self):
        used_locations = []
        for word in self.card_options:
            for i in range(2):
                available_locations = set(self.locations) - set(used_locations)
                random_location = random.choice(list(available_locations))
                used_locations.append(random_location)
                card = Card(word, random_location)
                self.cards.append(card)

    def create_row(self, num):
        row = []
        for column in self.columns:
            for card in self.cards:
                if card.location == f'{column}{num}':
                    if card.matched:
                        row.append(str(card))
                else:
                    row.append('  ')
        return row

if __name__ == '__main__':
    game = Game()
    game.set_cards()
    game.cards[0].matched = True
    game.cards[1].matched = True
    game.cards[2].matched = True
    game.cards[3].matched = True
    print(game.create_row(1))
    print(game.create_row(2))
    print(game.create_row(3))
    print(game.create_row(4))

['  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', 
'  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '
  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ']                           
['  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', 
'  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '
  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ']                           
['  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', 
'  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '
  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ']                           
['  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', 
'  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ', '
  ', '  ', '  ', '  ', '  ', '  ', '  ', '  ']