Transfer Data without duplicates from List A to List B

Hello Community, 
I'm struggling with the following issue:

- In List A I have column "colour". This column shows all possible colours (incl. duplicates). 

- Now I want to transfer List A to List B (same structure) without the duplicates.

 e.g. List A: 4x red --> List B: 1x red
        List A: 10x green --> List B: 1x green. 

I already tried "collections operations" with count Item but do not come to the prefered result.