@ xiexiaolei1984
Check with Costco first. If Costco won't refund your money, you can use this online refund request form to return the CD, if you purchased it within the last 60 days:
https://support.turbotax.intuit.com/forms/refund-request.jsp
If it's been longer than 60 days, then you'd need to phone TurboTax Support and tell them you were charged for both products since you used Online TurboTax by mistake instead of your Costco purchase, and see what they can work out for you.
