If an end-user (Contact) hits search with a keyword (say 'renewal'), a transaction id is generated (it is question_txn in okcs_stg_question table). It is unique in every session. But if someone hits browser 'Reload/Refresh' or 'Back' button, the same transaction id will get submitted making duplicate transaction ids. This would lead to duplicates in the okcs_stg_* tables then.  In order to avoid duplicate records being added to the okcs_stg_* tables, end-users should avoid using the browser's 'Reload/Refresh' or 'Back' buttons.

Also, should customer has custom KA Analytics reports based on the okcs_stg_* (okcs_stg_question, okcs_stg_annotation & okcs_stg_answers) tables, they may need additional filtering logic on transaction ids to avoid duplicates (if any) then.