And one more option is to use select duplicate. First you have to sort your data by Column 2 so you get the "latest" value as first (you might have to add row column to your data unless you nothing else to use to sort)
Then select Column 1 and use Select Duplicate Rows
You should now have the rows selected you wish to drop
You can then delete these or right click on rows and invert selection
Now you should have the rows you wish to have selected. You can also sort while having the selection if you wish to, but it will then select values from the Column 2
All of these different options have their own place.
-Jarmo