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One of those messages is valid, the other is a bug in phpmyadmin, by the looks of it.
The one about the primary key and index being the same is wrong, it's not taking into account the fact that the index is a multiple column index.
The message about two indexes on uname is true, it's unnecessary to have the single index on uname.
But those messages from myphpadmin are just there to bring it to your attention, they are not errors. The core developers could optimize the database somewhat by removing that extra index, it might save milliseconds when registering a new user, or updating user details, but it's not something to worry about.