I need help with **`difflib`** module.

I'm using difflib (<https://docs.python.org/3/library/difflib.html>) to compare 2 txt from url, line by line, and find duplications and missing lines. difflib flag with a '-' each line that it's only unique in one of those txt, but, when I run the code in python, I can see some lines flagged with '-' but those lines are present in both txt (it shouldn't, it should be present only in one of these txt, not both).

These are the 2 txt I compare:
<https://sumo.media/ads_1.txt> ---
<https://sumo.media/ads_2.txt>

Does anyone knows why it happens? I show you a screenshot at the end, with the output ussing difflib. Look at the line 'appnexus.com, 8610, DIRECT, f5ab79cb980f11d1' (which contains a '-' at the beginning, telling me that it's unique in <https://sumo.media/ads_1.txt>). This is not true because If I go to both txt urls, I can see this line in both txt.

What is strange is that if I analyze fewer lines, it works, but it does not work with lot of lines. I need to analyze large amount of lines so I need a solution. Any idea? any alternative maybe?

I also attach the code I run. The way I do this is getting both txt urls with request and asign a variable for each one. Then I apply a splitlines() and it returns an array with a value for each line (as string). I get 2 arrays, one for each txt. Finally I compare these 2 arrays to see which lines are duplicated or missing:

```
adstxt_1 = requests.get('http://www.sumo.media/ads_1.txt').text
adstxt_2 = requests.get('http://www.sumo.media/ads_2.txt').text

a = adstxt_1.splitlines()    # split line by line
b = adstxt_2.splitlines()    # split line by line

differ = difflib.Differ()
diffs = list(differ.compare(a, b))
for c in diffs:
    print(c)

```

What the code tells me (this line for ex start with '-' which should be unique in ads\_1.txt):
[python output](https://i.stack.imgur.com/ey5vX.png)

... but I see this same line in both .txt:
[/ads\_1.txt](https://i.stack.imgur.com/UbtHs.png) ---
[/ads\_2.txt](https://i.stack.imgur.com/wZFXp.png)

Appreciate any help!