Luke B. answered 06/08/19
My goal is to help you succeed in math and learn to love math!
Honestly, I'm not sure about which plugin to use, but your best bet may be to export the google sheet to an excel sheet and use the Remove Duplicates feature then re-import it into Google Sheets.
I just double checked my Google Sheets and under the "Data" menu option, there is now a "Remove Duplicates" option. It says "new" next to it so it looks like they just added it.
Let me know if I can help!