We keep track of all the cards you send and to whom. When you want to know the history of those cards you can go to the top of the "My Account" page (see it on the banner?) and click the "Sent Cards" area. You can then see a readout of your sent cards.
If you have a lot of sent cards, please be patient as they are rolled out for you to view.
If you want to search for a person to whom you sent a bunch of cards over time to avoid duplication, there is a search tool for you to do just that.
If you can't find the "Sent Cards" button, please view the attached illustration.