Deduplicate Single Cell Mysql

Question

I know there is plenty on here about duplicate rows and columns, but I have a single cell (intersection of row and column) that has multiple values that are comma delimited.

This would be somewhat trivial in some scripting language, but I want to keep in MySQL.

I have table checks and the last columns with there are two val1 values and only one should be returned.

+--------+----------+-------------+----------+----------------------------+
| id     | date     | doc         | amount   |  column_with_multiple_vals |
+--------+----------+-------------+----------+----------------------------+
| 346862 | 3/7/2017 | WIRE 111111 | 24651.33 | val1, val2, val3, val1     |
+--------+----------+-------------+----------+----------------------------+

Looking around I think this is how it might happen.

1. Load Data Local Infile
2. SET @myArrayOfValues = column_with_multiple_vals
3. I am a little uncertain of how to go about deduplicating the values in this simulated MySQL array.

I found this ariticle and seemed like it was on the right track of how of what I am looking for.

How can I simulate an array variable in MySQL?

SET @myArrayOfValue = '2,5,2,23,6,';

WHILE (LOCATE(',', @myArrayOfValue) > 0)
DO
    SET @value = ELT(1, @myArrayOfValue);
    SET @myArrayOfValue= SUBSTRING(@myArrayOfValue, LOCATE(',',@myArrayOfValue) + 1);

    INSERT INTO `EXEMPLE` VALUES(@value, 'hello');
END WHILE;