My program prints 20 questions instead of 10 when the program is twice

My program is supposed to print 10 questions and when it has finished it asks if the user would like to play again, if they press yes then the program is supposed to print 10 questions again but instead it prints 20. I have tried to fix this but it has been to no avail.

score = 0
def mainmenu():
print('What difficulty would you like to play on?')
print('1. Easy')                                
print('2. Medium')                #Three difficulties are shown from which the user can choose 
print('3. Hard')
print('4. Quit')
selection = int(input('Choose a number: '))
if selection == 1:
    choice = input('Are you sure you want to play on easy? [Y/N] ')
    if choice.lower() == 'y' or choice.lower() == 'yes':
        easy()                                                      #The user is asked to confirm if the difficulty they chose is the one they want
    if choice.lower() == 'n' or choice.lower() == 'no':
        print('Pick another difficulty')                            #If they say no they will be returned to the mainmenu using the define function
        mainmenu()
if selection == 2:
    choice2 = input('Are you sure you want to play on medium? [Y/N] ')
    if choice2.lower() == 'y' or choice2.lower() == 'yes':
        medium()
    if choice2.lower() == 'n' or choice2.lower() == 'no':
        print('Pick another difficulty')
        mainmenu()
if selection == 3:
    choice3 = input('Are you sure you want to play on hard? [Y/N] ')
    if choice3.lower() == 'y' or choice3.lower() == 'yes':
        hard()
    if choice3.lower() == 'n' or choice3.lower() == 'no':
        print('Pick another difficulty')
        mainmenu()
if selection == 4:
    exit()         

def easy():                                  #Easy is defined to allow for smoother access from the mainmenu 
global score
print('Heres come the questions!')
for i in range(10):                          #This process is repeated 10 times
    int_a = random.randint(0,10)
    int_b = random.randint(0,10)                #Random numbers are generated through the use of the random module
    operators = ['+']                           #The operators are made into a key to allow for them to be chosen randomly
    operators_value = random.choice(operators)
    question = str(int_a) + ' ' + str(operators_value) + ' ' + str(int_b)    #The two random numbers and the randomly chosen operators are made into a question 
    answerEasy = eval(question)                                              #The answer to the question is then found using the eval function 
    question += ': '

    questionsEasy.update({question:str(answerEasy)})        #The question and answer are put into a key to allow them to be matched up

for s in questionsEasy.keys():
    useranswer = input(s)
    if questionsEasy.get(s) == str(useranswer):          #If the user enters the correct answer 1 point is added to the score
        score += 1
        print('You got it Correct!')
    else:
        print('You got it incorrect :(')
print('Nice ' + name + '!' + ' You got ' + str(score) + ' out of 10!') 

you should define questionsEasy in easy function. The reason your program is printing 20 questions in second go is that questionsEasy is defined outside the easy function and is retaining its previous values and you are adding 10 more each time

If you are new to programming you can visualize your program using http://www.pythontutor.com/live.html#mode=edit