Hi @Tbabe,
It looks like you have two delimiters, is that correct? In the example are we evaluating two or four items?
If it is four items you could use some intersection, split and join functions to get the unique item values.
Below is an example with a couple of compose actions.
join(intersection(split(join(split(outputs('Compose'), ';'), ','), ','), split(join(split(outputs('Compose'), ';'), ','), ',')), ';')

