SQL & PL/SQL

HI,

First, I want to say I am not a strong sql developer but I am learning.

I am writing a ORACLE select statement with LISTAGG. It works but when I was validating the data, I saw duplicates like 1:1,1:1,2:2,2:2.

I verified that the database do have duplicate. The query is for two tables in a one to many relationship. Below is a snippet of my query but I changed the column names etc..

how can I modified the following query to return unique values for each person?

I hope to achieve results like

1  John M. Doe 1:1, 2:2, 3:3, 4:4

NOT this

1 John M. Doe 1:1, 1:1, 2:2, 2:2, 3:3

I was told to add a DISTINCT to a subquery but  not sure how to achieve this. Any help is greatly appreciated. Thanks.

Thanks

    SELECT Table1.PERSON_ID,
           Table1.FIRST_NAME,
           Table1.MIDDLE_NAME,
           Table1.LAST_NAME,
   
    LISTAGG(case 
            when Table2.DESCRIPTION = '1' then '1:1'
            when Table2.DESCRIPTION = '2' then '2:2'
            when Table2.DESCRIPTION = '3' then '3:3'
            when Table2.DESCRIPTION = '4' then '4:4'
            when Table2.DESCRIPTION = '5' then '5:5'
            when Table2.DESCRIPTION = '6' then '6:6'
            when Table2.DESCRIPTION = '7' then '7:7'
            when Table2.DESCRIPTION = '8' then '8:8'
            when Table2.DESCRIPTION = '9' then '9:9'
    
   
          else ''
   
     end, ',') 
    WITHIN GROUP (ORDER BY Table2.DESCRIPTION ) 
   
    FROM Table1
    LEFT JOIN Table2
   
    ON Table2.PERSON_ID = Table1.PERSON_ID
    GROUP BY Table1.PERSON_ID,Table1.FIRST_NAME,Table1.MIDDLE_NAME, Table1.LAST_NAME