Welcome to the community!
Unfortunately, SerpWatch temporarily stopped deduplicating keywords. The reason being keywords in languages containing diacritics (accent marks).
For instance, there have been cases of two seemingly identical keywords in the Greek language where the accent mark would completely change the word meaning. In order to allow users to track both of these keywords, developers made “duplicates” possible.
However, we have received a lot of feedback on this and we are working on resolving this issue.
In the meantime, I suggest that you import all existing and new keywords into Google Sheets and use their ‘Remove Duplicates’ feature.
You can also leave a feature request which serves as a voting tool for upcoming features.
Hope this helps and thank you for your feedback!