Answer 1

Are the tuples duplicate rows in a table? To avoid this, you can configure the table with a unique constraint (e.g. a primary key).
To check for duplicate data, run a query to join the table to itself on the non-unique fields and use something unique, like another column or a pseudo column like ROWID, RID or the row_number function.
Alternatively, run a query before inserting new data to ensure the new tuple data is unique.