MySQL select and group by with concat

I have 2 table:

properties:

id,name
10,Weight
11,Color
12,Width
13,Height

product_prop:

id,product,prop,name
1,171243,10,12.56
2,171243,11,white
3,171243,12,500
4,127865,10,10.01
5,127865,11,white

My query:

SELECT p.id, p.name AS propName,
       GROUP_CONCAT(DISTINCT pp.name SEPARATOR ',') AS propValue,
       GROUP_CONCAT(DISTINCT pp.id SEPARATOR ',') AS propKey
FROM properties p 
INNER JOIN product_prop pp ON p.id = pp.prop
WHERE pp.product in (171243, 127865)
GROUP BY p.id, p.name; 

The result:

The first and last row its ok. The 2nd row propKey i can see the only first found (2), because the 5 its equal the 2 (with name in product_prop table).

I suggest you could do this with a subselect that first identifies unique property values per property, then an outer select that does your aggregation:

SELECT
    p.id, p.name AS propName,
    GROUP_CONCAT(upp.propValue) AS propValue,
    GROUP_CONCAT(upp.propKey) AS propKey
FROM properties p
INNER JOIN (
    SELECT 
        pp.prop,
        pp.name AS propValue,
        MIN(pp.id) AS propKey
    FROM product_prop pp
    WHERE pp.product in (171243, 127865)
    GROUP BY pp.prop, pp.name
) upp ON p.id = upp.prop
GROUP BY p.id, p.name;