Conditional formatting - highlight unique/duplicate values

Hi
I created 2 rules to highlight duplicate and unique value respectively using the following formulas:

For duplicated
=COUNTIF($A$2:$A$20,A2)>1
for unique
=COUNTIF($A$2:$A$20,A2)=1

I also selected a cell and the inserted Data Validation list with the following values

- Duplicate
- Unique

Can I like this cell to the conditional formatting rules, so if user select Duplicate then it will execute the first formula and if the user selected unique then it will execute the second formula?
Please see attached file for more info. Thank you very much