Consilidate accounts?

I have a problem with Mozilla SSO. I’ve created an account (to use it with LLVM Discourse group), and successfully logged in. After setting up the preferences to my liking, I logged off.

Problem: since then I am unable to login as that user again! Upon seeing my email address, Mozilla forced me to create another account, from which this cry for help is posted.

How do I reclaim my first account, or merge these two?