when I create a basic card, I have 2 card created : card 1 and card 2. So when I review I have 2 exemple of the same card. If I delete the card 2 that also delate card 1.
Do you know how to make it only create one card ?
When you delete a card from the browser, you are actually deleting a whole note. A single note can have multiple cards. To illustrate, if you think back to physical flashcards, you have a front and a back, and you can study front to back or back to front. In Anki, each of these directions would be set up as a separate card for the same note, and you cannot delete the cards individually, so far as I know.
If you only want one direction, you will want to assign the note to a note type that has only one card. By default, the basic card is exactly that, while “Basic (and reversed card)” by default matches what you are describing. It is possible you selected the wrong note type, or it is also possible you edited the Basic type to have a second card.
A read through this subsection and one following will help understand:
https://docs.ankiweb.net/#/editing?id=adding-cards-and-notes
And if you want to do further editing of the note types, here is further guidance:
https://docs.ankiweb.net/#/templates/generation
Thanks you very much !!
indeed my basic card style had been changed to create two card.