I have a class `AttachDoc` with property: `DOCUMENT_ID, DOC_NAME`
The list is populated with duplicates
Ex:

```
1   Name1
2   Name2
2   Name2
3   Name3

```

The second Name2 is a duplicate (based on id and name) and I wanna reset its name, but keeping that row. The expected outcome is:

```
1  Name1
2  Name2
2  null
3  Name3

```

How could I manage it using LINQ? Thank you!