<Number> records match the selection. Delete them all?

Because the Data pane doesn't include a field whose values uniquely identify each record, such as a customer ID or order ID, the result set contains other records that match the one you want to delete. If you delete the selected record, Microsoft Query will also delete any identical records.

To distinguish records before you begin to edit data, make sure to add all the fields from the underlying table or to create a unique index in the table.