If taxonomy entries are showing up as duplicated, there is likely an issue with the taxonomy file that has been uploaded. The most likely issue is that some entries contain whitespaces before or after the desired entry, which is causing them to display in the UI twice.
To remove these, first remove any unwanted whitespaces from the taxonomy file and re-upload it to ensure that all datasets have been moved to the correct taxonomy path. After this, the wrong taxonomy path can then be deleted within the UI.