import re
p = re.compile(r'var\d+(?:(?!var\d).)*?secondVar', re.DOTALL)
test_str = "var12.1\na\na\ndsa\n\n88\n123!!!\nsecondVar12.1\nvar12.1\na\na\ndsa\n\n88\n123!!!\nsecondVar12.1"
print(p.findall(test_str))
aW1wb3J0IHJlCnAgPSByZS5jb21waWxlKHIndmFyXGQrKD86KD8hdmFyXGQpLikqP3NlY29uZFZhcicsIHJlLkRPVEFMTCkKdGVzdF9zdHIgPSAidmFyMTIuMVxuYVxuYVxuZHNhXG5cbjg4XG4xMjMhISFcbnNlY29uZFZhcjEyLjFcbnZhcjEyLjFcbmFcbmFcbmRzYVxuXG44OFxuMTIzISEhXG5zZWNvbmRWYXIxMi4xIgpwcmludChwLmZpbmRhbGwodGVzdF9zdHIpKQ==