Migrate MySQL tables to new server with same tables already on it?
So, you want to import the new data without overwriting and no duplicate keys, right? I'm no expert, but as I see it, you can either:


Remove the current data and import the whole old DB,  
Use --ignore or --replace on mysqlimport - either won't duplicate rows (they'll either --replace existing rows or --ignore duplicates),  
mysqldump without creating the database, the table and using the Insert Ignore option (--insert-ignore), so it'll insert the data and skip the duplicate keys,  
Use --force when importing, to skip errors while inserting, this way if there's already one row with the key being inserted, it won't generate an error, just skip it and go to the next insert.


You can look up another already answered questions and try to find the best solution: here or here.

I tried with the --insert-ignore option on mysqldump and when importing I had no errors, the new data was inserted with no duplicates.