Implementation depends on your scenario
Option 1 - Truncate the data first and load data from Excel every time
Option 2 - Load data from Excel to Staging table and run SP to get only unique records loaded to final table
Option 3 - After excel load, run SP to remove duplicate, unwanted data from your final table
Reference:
https://www.mssqltips.com/sqlservertip/1918/different-strategies-for-removing-duplicate-records-in-sql-server/
https://www.mssqltips.com/sqlservertip/4486/find-and-remove-duplicate-rows-from-a-sql-server-table/
Please don't forget to Accept Answer and Up-vote if the response helped -- Vaibhav