Děkuji zejména Warm_spiderovi.

Zdá se že funkční řešení pro MySQL vypadá následovně:

SELECT additional_name, min( additional_value ) , case when additional_value regexp '^[0-9]' then max( additional_value ) else additional_value end as val
FROM products_additional
WHERE TYPE = 'ADI'
AND products_id
IN ( 61508, 61501, 61512, 61507, 61500, 61511, 61509, 61510 )
GROUP BY additional_name
ORDER BY additional_name, additional_value