You can't redeem your Club Nintendo code on the same account, but you can add another account to yours if you make yours a Family Account (not sure all the details, but they're out there). You CAN redeem the eShop code that Nintendo gives you on the same account though, just not the Club Nintendo coins code to get the eShop code.
http://en-americas-support.nintendo...2303/~/how-to-add-members-to-a-family-account
AWW YEAH