Você pode adicionar aliases aos campos:
SELECT
a.id,
a.name,
a.category_id,
b.id AS catId,
b.name AS catName
FROM
product AS a
LEFT JOIN
category AS b ON a.category_id = b.category.id
SELECT
a.id,
a.name,
a.category_id,
b.id AS catId,
b.name AS catName
FROM
product AS a
LEFT JOIN
category AS b ON a.category_id = b.category.id