My credit card is due to expire next month and I received replacements for myself and my husband yesterday. We both received two identical copies of each card. My two cards arrived in the same envelope and my husband's arrived in two separate letters.
Why have we both been sent two cards? Are we OK to keep both and use one, or would it be best to destroy one of the copies...or will they work at all? Please could you advise?

Many thanks
Emma