I want to select the second lowest DATE grouped per ID (if more than one DATE) and then mutate the result into an new column (NEW).

```
DF<-tibble::tribble(
  ~ID,        ~DATE,
   1L, "2001-01-01",
   2L, "2002-02-02",
   2L, "2002-02-02",
   3L, "2004-04-04",
   3L, "2005-05-05",
   4L, "2006-06-06",
   4L, "2006-06-06",
   4L, "2007-07-07"
  )

# A tibble: 8 × 2
     ID DATE      
  <int> <chr>     
1     1 2001-01-01
2     2 2002-02-02
3     2 2002-02-02
4     3 2004-04-04
5     3 2005-05-05
6     4 2006-06-06
7     4 2006-06-06
8     4 2007-07-07

```

Desired output:

```
# A tibble: 8 × 3
     ID DATE       NEW       
  <int> <chr>      <chr>     
1     1 2001-01-01 NA        
2     2 2002-02-02 NA        
3     2 2002-02-02 NA        
4     3 2004-04-04 2005-05-05
5     3 2005-05-05 2005-05-05
6     4 2006-06-06 2007-07-07
7     4 2006-06-06 2007-07-07
8     4 2007-07-07 2007-07-07

```

Best regards,
H