Hi John
As with all these events you only notice the results after you have done the deed.
I have no idea how they could have been linked.
Because of the low visual impact of the linking I was only aware of this happening by chance. I think there are 2 possible scenarios:
The first might have been signing into the Yahoo app, but I can't remember the incident so that's not helpful.
Secondly, for some reason they were linked as suggested though a third party like Facebook, again I don't remember having any options presented that would do this.
It is worrying as these were two completely separate accounts neither uses the other as a rescue email, and there is no reference to either. There is a big push to get all acconts under one roof for some reason eg even Google wants to list everything on a sign up page.
There are numerous solutions out there but all the one I have found refer one to places and options that either do not work or do not exist, as with the one you sjowed me.
Frustrating is the word.
The only solution I can see is to permanently delete one's linked account, then resurrect it (this is possible within I think 3 months but don't quote me.), and then see if they are unlinked. This sounds dangerous to me, as how does one know if this will work until after the event...
Mike