"Duplicate entries will be overwritten"

But this message does not tell the truth.

Depends on how the table is defined:

• If you are inserting a duplicate key where it is not allowed, this new row will not be inserted.
• If you are allowed to insert this row, you really end up with duplicates, but there is no overwriteen. (You can get rid of the duplicates in your application, but that's a different issue. Your error/warning message for your database operation still should reflect the result of that insert statement.)