Copying without affecting original deck

Hello, everyone,
I am a first time user, trying to use Anki for New Testament Greek and German. My version is 2.1.35. I have a question, that might seem simple. How do I just copy a deck without affecting or stealing cards from another deck ?(I guess, that’s a parent deck) I like to study both ways (with or without flipping cards), but I messed up the decks by choosing in Browse and flipping. Thank you for your time,