Multidropdown input is duplicated using Set List

I am selecting a user with a check box and save it in a list of users in a state.

Now my problem is, whenever I try to run a Make changes to my list of users with the Multidropdown value, it duplicates the data.

Example:

image

When I run this one I get,

John - Test 1
Terry - Test 1

Then I run again, I get

John - Test 1, Test 1
Terry - Test 1, Test 1

I already tried Add List and it’s working but the problem is whenever I tried to leave Multidropdown to a blank data, the data stays there and it does not replace the data with blank data compared to the Set List.