user1
user2

URL GOTO=https://www.url.com/example
TAG POS=1 TYPE=BUTTON ATTR=TXT:Follow

URL GOTO=https://www.url.com/example
TAG POS=1 TYPE=BUTTON ATTR=TXT:Follow

with open('textfile1.txt') as f1, open('textfile2.txt') as f2:
    for l, r in zip(f1, f2):
        print(r[:r.find('/example') + 1] + l)

URL GOTO=https://www.instagram.com/user1

user2

URL GOTO=https://www.url.com/user1
TAG POS=1 TYPE=BUTTON ATTR=TXT:Follow

URL GOTO=https://www.url.com/user2
TAG POS=1 TYPE=BUTTON ATTR=TXT:Follow