I'm starting out with regular expressions and grep and I want to find out how to do this. I have this list:

```
1. 12493 6530
2. 12475 5462
3. 12441 5450
4. 12413 5258
5. 12478 4454
6. 12416 3859
7. 12480 3761
8. 12390 3746
9. 12487 3741
10. 12476 3557
...

```

And I want to get the contents of the middle column only (so NF==2 in awk?). The delimiter here is a space.

I then want to find which numbers are there more than once (duplicates). How would I go about doing that? Thank you, I'm a beginner.