One Click Registration from Marketplace

We are adding products to our website via the Marketplace plugin and added the feature (via the Marketplace plugin) for require an account in order to purchase a product. I am not sure if there is a problem with the marketplace plugin because it takes the user to a registration page that show the Facebook account details, vs the one click registration, that we have set up via the Ultimate Facebook plugin. Then when you click to register, it loops and refreshes the screen. It may be that we used an account that was already used. If that is the case, then should it not just login the user? Am I missing something in a setting or is the marketplace plugin not communicating nicely with Ultimate Facebook?