The secret to this amazing card trick is the wallet. It is a trick wallet. Take out both cards and you will see that the 7 of clubs is a fake blank card and that the printing is actually part of the wallet sleeve. It’s an optical illusion.
Here is how the trick should look to your audience and be performed…
Show the wallet with two cards inside. Take out the red 7 of diamonds and place it face up on the table. Then turn your wallet over and remove the other 7 of clubs (but actually not a 7 of clubs - it is blank). You can then casually show that nothing is left is in the wallet. This card goes on top of the 7 of diamonds face down so you do not reveal the blank face.
By magically pushing on the cards your audience will believe that the ink has magically transferred from one card to the back of the other card.
Practice your magic and make it believable. See the below video to see the magic trick in action.