import os


with open('task2_data_1.txt', 'a') as first, open('task2_data_2.txt') as second:
    second_data = second.read()
    first.write('\n\n\n')
    first.write(second_data)

os.rename('task2_data_1.txt', 'task2_data_all.txt')
os.remove('task2_data_2.txt')