Whenever working with huge term sets, you can hardly avoid having duplicates. Even if an import will skip them, if you process them programmatically (eg: PowerShell import & processing) it’s better & easier to work on a proper set than always checking for duplicates. It’s also welcome when you send this back & forth to consumers so they can easily refine their taxonomy without missing with duplicates.
Turns out it’s pretty simple in Excel, you just highlight the area you want to filter, go to data > Filter (Advanced) you specify a region next to your current one (you can’t do this on another sheet) and you’ll have only the unique entries. Copy / paste this selection on a new document and you now have your filtered set, with only unique entries. Hard to beat when dealing with taxonomies that have thousands of terms 🙂