SELECT with equal chance between same IDs - MySQL
To select a random id with equal chances:

SELECT DISTINCT id
FROM tableX
ORDER BY RAND()
LIMIT 1 ;


You can combine the above in a subquery (derived table) to find a single row:

SELECT t.*
FROM tableX AS t
  JOIN
  ( SELECT DISTINCT id
    FROM tableX
    ORDER BY RAND()
    LIMIT 1
  ) AS i
    ON i.id = t.id
ORDER BY RAND()
LIMIT 1 ;