Short answer, no.
Long answer, the desktop program (installed on your own computer from a CD or download) and the online program have different capabilities and different pricing structures. Turbotax is the only seller for the online program, while many stores sell the desktop program, often at a discount. Costco is a special case since they actually make most of their annual profit from membership fees so can afford to sell many items below their own wholesale cost.
The desktop program allows you to file more than one return for the same basic installation, but the files only are on your own hard drive so you are responsible for security and backups. The online program can be accessed from any web browser and is backed up by Turbotax, but each online account can only file one return and each new return will require a separate online account and separate fee.
