from tkinter import Tk, simpledialog, messagebox, Canvas

root = Tk()

#считали данные
results = {}
file = open('records.txt','r',encoding='utf-8')
for line in file:
    line = line.rstrip() #line = 'allena,10'
    people, score = line.split(',') # 'allena' '10'
    results[people] = score
file.close()

score = 120
i = 0
while i < 3:
    people = simpledialog.askstring('Сохраним результат','Ваше имя?')
    if people in results:
        if int(results[people]) < score:
            results[people] = str(score)
    else:
        results[people] = str(score)
        file = open('records.txt','a',encoding='utf-8')
        file.write(people+','+str(score)+'\n')
        file.close()
    i += 1