As said, just take your Deck to your pocket after the trick is done, and if they ask, just have a matching deck to switch to. I doubt any layman will assume you're switching it as it has not happened to me yet. Don't allow them to examine anything right away. Pocket the ID immediately and if they ask, switch it. If they don't then simply don't.
If you want, you can be bold and do the switch while their distracted by the card. Using patter such as "I almost forgot about that one" pointing to the card. You say this after boxing the ID. Switch it quickly on the offbeat, open it back up and throw the card on top. From here, you can take it further by flipping the deck face up and copping the card off the bottom now, or you can simply palm it while handing over the deck. Unnecessary but you end SO CLEAN.
Either or, it's an effect that has fooled the best. I have small subtleties I use when performing. If you would like further tips and such, feel free to PM me!