I am merging incoming attributes in Aggregator. I concatenate the values from a field but I am getting duplicate values. How do I create a cleaner attribute without duplicates?

I am merging incoming attributes in Aggregator. I concatenate the values from a field but I am getting duplicate values. How do I create a cleaner attribute without duplicates?
Hi
A solution I can think of is:
Thanks. That was the approach I started to use after my post.