Update values from one table to another where key values are not unique
This is impossible. 

+------+------+------------------+-------+------------+-------+
| Null | Null | BLANK-ROSTER NUM | 34.30 | 2018-01-01 | 12345 |
| Null | Null | BLANK-ROSTER NUM | 34.30 | 2018-01-01 | 77777 |
| Null | Null | BLANK-ROSTER NUM | 34.30 | 2018-01-01 | 66666 |
+------+------+------------------+-------+------------+-------+


can't be updated from 

+--------+-------+------------------+-------+------------+
| SMITH  | JOHN  | BLANK-ROSTER NUM | 34.30 | 2018-01-01 |
| JONES  | JAMES | BLANK-ROSTER NUM | 34.30 | 2018-01-01 |
| WILSON | JACK  | BLANK-ROSTER NUM | 34.30 | 2018-01-01 |
+--------+-------+------------------+-------+------------+


There is absolutely no reason to choose Jack Wilson among other persons for the row having 66666 in the last column. Also there is no visible sorting for both tables so we can't use it somehow.