Complex sentence: The Kalki Purana states Koka and Vikoka are the grandsons of "Shakuni" and sons of "Bakasura", who are not to be confused with the Shakuni and Bakasura from the Mahabarata-former are father and son, whereas the latter are unrelated.
Split into simpler sentences: The Kalki Purana states they are the grandsons of "Shakuni" and sons of "Bakasura". The former are father and son, whereas the latter are unrelated.