Having 2 separate decks for vocabulary learning

[suiyuan]

I think the instructions here are correct:

Duplicating A Deck and then flipping the back and the front of all the cards in the duplicated deck only

At first, you can change the note type to Basic (and reversed card) so you will have both cards front-back and back-front (English-French and French-English). If you really need to duplicate the deck try this: Export your deck Make a second user in Anki Import the deck Rename the deck Change the card template so French is on front an English is on back Export it, switch the user and import the new deck.

However, maybe you need to rename the deck and the note type (Tools > Manage Note Types), so that when reimporting to your main profile these are considered different notes.

I think that might work.