Duplicate data is common when lists are imported, copied or combined from multiple sources. Before deleting anything, decide which columns define a true duplicate. Two identical names may be valid if they belong to different orders or dates.
Start with the obvious checks
Make a backup first. Use Excel’s Remove Duplicates tool after selecting the full table and choosing the columns that should be compared. Alternatively, use UNIQUE or COUNTIFS to identify duplicates before deleting them.
What else to check
For recurring data cleanup, an automated process can be safer than manually removing duplicates every week.
When to get help
Get help building a repeatable spreadsheet workflow.