User blog comment:MisterWoodhouse/Resolving your overlapping username on Fandom and Gamepedia/@comment-5082092-20200421224030/@comment-24006128-20200421224616

Once we have the login system unified on the UCP, a Fandom user will be able to go onto Gamepedia on their same account and vice versa.

The problem becomes when there's a conflict of the usernames. By connecting the ones which are owned by the same user, we resolve that conflict and they can move across the wikis normally.

The usernames with conflict but no common owner need to be resolved so that only one account exists with any given username. That will come next, through a mixture of automatic checks and manually intervention by staff.