Pre-Registration Provider Account Linking: Lock In and Conflict

Testing out scenarios when someone changes their mind over which service to use, or fails to complete and returns later to use another.

#1) Seems there is no way to back out of using a service. Once you've linked it (pre-registration) it's stuck. Even clearing browser cookies won't kill it. The only way to use another service would be to revisit the login page/block and click the sign in link then select "use another service".

#2) If one does click the "use another service" link, then multiple services are all set within the session, causing several problems of varying degree...
A) The final displayed service choice is not honored.
In my case I tried Twitter, then Facebook, then Yahoo (all pre-account creation... really pushing it). While finalizing it displayed FB as the linking account, however it ended up with Yahoo.

B) Different service providers at different URLs
http://example.com/user/register
http://example.com/user/register?destination=user

Believe all of this could be solved with: #1) "Use another service" link on the registration page, #2) anytime someone clicks "use another service" even within existing popup janrain should clear the session of other accounts.