Spreadsheet: 45332d1244093005-sort-grade-1st-date-2nd-simultaneously-solution-sortgrade-and-date
Sheet: Solution

STEP-1 |  |  |  |  |  | Apply below formulas
 |  | Data |  |  |  |  |  |  | if you have only 4 char in column D "A 54" then below formula will also work
 |  | Name | GRADE | Date |  | GRADE | Date
 |  | A | A 54 | 1989-10-03 00:00:00 | 1.004 | 14 | 12 |  | 1 | 54
 |  | S | A 41 | 1995-06-01 00:00:00 | 8.005 | 7 | 6 |  | 8 | 41
 |  | Q | A 36 | 1997-06-01 00:00:00 | 10.006 | 5 | 5 |  | 10 | 36
 |  | W | A 54 | 1990-01-20 00:00:00 | 1.007 | 13 | 11 |  | 1 | 54
 |  | E | A 48 | 1995-06-01 00:00:00 | 4.008 | 11 | 6 |  | 4 | 48
 |  | R | A 26 | 1999-09-14 00:00:00 | 12.009 | 3 | 3 |  | 12 | 26
 |  | G | A 44 | 1992-09-14 00:00:00 | 5.01 | 10 | 9 |  | 5 | 44
 |  | H | A 54 | 1992-09-14 00:00:00 | 1.011 | 12 | 9 |  | 1 | 54
 |  | J | A 44 | 1995-06-01 00:00:00 | 5.012 | 9 | 6 |  | 5 | 44
 |  | K | A 44 | - | 5.013 | 8 | 0 |  | 5 | 44
 |  | L | A 17 | 1999-09-14 00:00:00 | 14.014 | 1 | 3 |  | 14 | 17
 |  | PO | A 29 | 2001-06-22 00:00:00 | 11.015 | 4 | 1 |  | 11 | 29
 |  | N | A 41 | - | 8.016 | 6 | 0 |  | 8 | 41
 |  | V | A 26 | 2001-06-22 00:00:00 | 12.017 | 2 | 1 |  | 12 | 26
 |  |  |  |  |  |  |  |  |  |  |  | 0
STEP-2 |  | - Now Copy the Data from C2:H17 and Paste as special > Formats & again Vales
 |  | Data
 |  | Name | GRADE | Date |  | GRADE | Date
 |  | A | A 54 | 1989-10-03 00:00:00 | 1.004 | 14 | 12
 |  | S | A 41 | 1995-06-01 00:00:00 | 8.005 | 7 | 6
 |  | Q | A 36 | 1997-06-01 00:00:00 | 10.006 | 5 | 5
 |  | W | A 54 | 1990-01-20 00:00:00 | 1.007 | 13 | 11
 |  | E | A 48 | 1995-06-01 00:00:00 | 4.008 | 11 | 6
 |  | R | A 26 | 1999-09-14 00:00:00 | 12.009 | 3 | 3
 |  | G | A 44 | 1992-09-14 00:00:00 | 5.01 | 10 | 9
 |  | H | A 54 | 1992-09-14 00:00:00 | 1.011 | 12 | 9
 |  | J | A 44 | 1995-06-01 00:00:00 | 5.012 | 9 | 6
 |  | K | A 44 | - | 5.013 | 8 | 0
 |  | L | A 17 | 1999-09-14 00:00:00 | 14.014 | 1 | 3
 |  | PO | A 29 | 2001-06-22 00:00:00 | 11.015 | 4 | 1
 |  | N | A 41 | - | 8.016 | 6 | 0
 |  | V | A 26 | 2001-06-22 00:00:00 | 12.017 | 2 | 1
STEP-3 |  | - Just Sort the Data on the basis of Grade & Date in Descedning Order or as per your requirements
 |  | - it will be sorted out as per your requirements
 |  | SORTED DATA
 |  | Data
 |  | Name | GRADE | Date |  | GRADE | Date
 |  | A | A 54 | 1989-10-03 00:00:00 | 1.004 | 14 | 12
 |  | W | A 54 | 1990-01-20 00:00:00 | 1.007 | 13 | 11
 |  | H | A 54 | 1992-09-14 00:00:00 | 1.011 | 12 | 9
 |  | E | A 48 | 1995-06-01 00:00:00 | 4.008 | 11 | 6
 |  | G | A 44 | 1992-09-14 00:00:00 | 5.01 | 10 | 9
 |  | J | A 44 | 1995-06-01 00:00:00 | 5.012 | 9 | 6
 |  | K | A 44 | - | 5.013 | 8 | 0
 |  | S | A 41 | 1995-06-01 00:00:00 | 8.005 | 7 | 6
 |  | N | A 41 | - | 8.016 | 6 | 0
 |  | Q | A 36 | 1997-06-01 00:00:00 | 10.006 | 5 | 5
 |  | PO | A 29 | 2001-06-22 00:00:00 | 11.015 | 4 | 1
 |  | R | A 26 | 1999-09-14 00:00:00 | 12.009 | 3 | 3
 |  | V | A 26 | 2001-06-22 00:00:00 | 12.017 | 2 | 1
 |  | L | A 17 | 1999-09-14 00:00:00 | 14.014 | 1 | 3
 |  | Solution
 |  | Name | GRADE | Date
 |  | A | A 54 | 1989-10-03 00:00:00
 |  | W | A 54 | 1990-01-20 00:00:00
 |  | H | A 54 | 1992-09-14 00:00:00
 |  | E | A 48 | 1995-06-01 00:00:00
 |  | G | A 44 | 1992-09-14 00:00:00
 |  | J | A 44 | 1995-06-01 00:00:00
 |  | K | A 44 | -
 |  | S | A 41 | 1995-06-01 00:00:00
 |  | N | A 41 | -
 |  | Q | A 36 | 1997-06-01 00:00:00
 |  | PO | A 29 | 2001-06-22 00:00:00
 |  | R | A 26 | 1999-09-14 00:00:00
 |  | V | A 26 | 2001-06-22 00:00:00
 |  | L | A 17 | 1999-09-14 00:00:00